enamines and ylides.docx
TRANSCRIPT
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ENAMINES AND
YLIDES
M.SC-II (SEM-III)
ORGANIC CHEMISTRY
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PREPERATION OF SULFOXIDES:
R S R1
O
Oxidation of alkyl sulphides by :
SR R1
+ H2O2 R S R1O
+ OH2
SCH3 CH3 H2O2 R S R1
O
OH2
Oxidation of alkyl sulphides using per-acids:
SR R1 R''COOOH CH3 S CH3
O
+ R''COOH
Generation of carbanion from sulfoxide:
CH3 S CH3
OBuLi/LDA/PhLi
or MeLiCH3 S CH2
-
O
Li+
+ Bu-Hmethyl sulphinyl carbanion
Application in C-C bond formation:
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CH3 S CH3
O
CH3 S CH2-
O
Li+
OO
R S CH3
-keto sulphoxide
R Cl
O
- LiCl
n -BuLi
Red Al-Hg
CH3 CH3
O
i.e RCOCH 3
ketone
1)
CH3 S CH2-
O
+R
X
O
CH3
S R
Redn CH3
R
2)
OO
CH3
S
CH3
NaOH
BrCH2COOMe
Redn
NaBH4
OO
R
S
CH3
CH2COOMe
OOH
R
S
CH3
CH 2COOMe
3)
-MeOH
O
O
S
CH3
O
R
Redn
O
O
R
Lactone
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O
(CH2)n
H
S PhLDA
RIO(CH2)n
R
S Ph R
(CH2)n
CH3S
PhH
2O
(CH2)n
OH
5)
O
CH3
S
CH2
CH3
CH3 I
CH3
LDA
SCH3
CH2
CH3
CH3
Ph
O
S PhOCH3
CH3
CH3
H2O
CH3
CH3
OH
CH3
6)
PREPARATION OF SULPHONES:
RS
R
O O
Addition of sulphuric acid to polar C=C bonds:
RS
H
O O+
H
H
Z
H
CH3 S
O
O
Z
H
Here, R=donor oracceptor group
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Z= withdrawing group
O
+ PhSO 2H
O
H
H
SO2Ph
Addition of sulphuric acid to polar C=O or C=N bond:
SO O
HR
+ R1O
H RSO 2
OH
R1
S
O O
HR
+R
1NR'' RSO 2 R'
NHR''
O
O
O
CH3
CH3+ CH3 SO2H
O
SO2O
CH3
CH3
OH
CH
Generation of carbanion from sulphones:
CH3 SR1
O
O
n -BuLi or
LDA orPhLi
O
CH3 S
CH-
R1
O
Carbanion Now, this carbanion formed can be used in various C-C bond forming reactions.
Applications in C-C bond formation:
Formation of cyclopropane derivatives:
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O
Ar-
S
Cl
On -BuLi
LDA
O
Ar-
S
CH-
ClO
Ar --SO2
Ni -Hg
i)
O
Ph
S O TS
O
LDA
O
PhS
CH-
O TS
OPh S
O
O
n-BuLi
C-Ph S
O
O
CH3IPh S
O
O CH3
CH3
ii)
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O
CH3 S R
O+
Br
Br
LDA CH3 S
O
O
C-
R
Br
CH3 S
O
O
C-
R
Ni -Hg
R
iii)
Bamford-Steven Reaction
The BamfordStevens reaction is achemical reactionwhereby treatment
oftosylhydrazoneswith strong base givesalkenes.[1][2][3]
It is named for the British
chemistWilliam Randall Bamfordand the Scottish chemistThomas Stevens Stevens(1900
2000). The usage ofaprotic solventsgives predominantly Z-alkenes, whileprotic solventgives a
mixture of E- and Z-alkenes.
The treatment of tosylhydrazones with alkyl lithium reagents is called theShapiro reaction.
Reaction mechanism
The first step of the BamfordStevens reaction is the formation of the diazo compound 3.[4]
In protic solvents, the diazo compound 3 decomposes to thecarbenium ion5.
http://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/Carbenium_ionhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Tosylhydrazonehttp://en.wikipedia.org/wiki/Tosylhydrazonehttp://en.wikipedia.org/wiki/Tosylhydrazonehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-bamford1952-1http://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-bamford1952-1http://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-adlington1983-3http://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-adlington1983-3http://en.wikipedia.org/w/index.php?title=William_Randall_Bamford&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=William_Randall_Bamford&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=William_Randall_Bamford&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Thomas_Stevens_Stevens&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Thomas_Stevens_Stevens&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Thomas_Stevens_Stevens&action=edit&redlink=1http://en.wikipedia.org/wiki/Aprotic_solventhttp://en.wikipedia.org/wiki/Aprotic_solventhttp://en.wikipedia.org/wiki/Aprotic_solventhttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Protic_solventhttp://en.wikipedia.org/wiki/Protic_solventhttp://en.wikipedia.org/wiki/Protic_solventhttp://en.wikipedia.org/wiki/Shapiro_reactionhttp://en.wikipedia.org/wiki/Shapiro_reactionhttp://en.wikipedia.org/wiki/Shapiro_reactionhttp://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-creary1986-4http://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-creary1986-4http://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-creary1986-4http://en.wikipedia.org/wiki/Carbenium_ionhttp://en.wikipedia.org/wiki/Carbenium_ionhttp://en.wikipedia.org/wiki/Carbenium_ionhttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_Reaction_Scheme.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismA.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_Reaction_Scheme.pnghttp://en.wikipedia.org/wiki/Carbenium_ionhttp://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-creary1986-4http://en.wikipedia.org/wiki/Shapiro_reactionhttp://en.wikipedia.org/wiki/Protic_solventhttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Aprotic_solventhttp://en.wikipedia.org/w/index.php?title=Thomas_Stevens_Stevens&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=William_Randall_Bamford&action=edit&redlink=1http://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-adlington1983-3http://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-bamford1952-1http://en.wikipedia.org/wiki/Bamford%E2%80%93Stevens_reaction#cite_note-bamford1952-1http://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Tosylhydrazonehttp://en.wikipedia.org/wiki/Chemical_reaction -
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In aprotic solvents, the diazo compound 3 decomposes to the carbene 7.
Julia olefinationThe Julia olefination (also known as the JuliaLythgoe olefination) is thechemical
reactionofphenylsulfones(1) withaldehydes(orketones) to givealkenes(3) after alcohol
functionalization and reductive elimination usingsodium amalgam[1][2]orSmI2.[3]The reaction is
named after the French chemistMarc Julia.
This transformation highly favors formation of the trans-alkene.
All four steps can be carried out in a single reaction vessel, and use of R3X is optional. However,
purification of the sulfone intermediate 2 leads to higher yield and purity. Most often
R3
isacetylorbenzoyl, withacetic anhydrideorbenzoyl chlorideused in the preparation of 2.
Several reviews have been published.[4][5]
Reaction mechanism
http://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Phenylhttp://en.wikipedia.org/wiki/Phenylhttp://en.wikipedia.org/wiki/Sulfonehttp://en.wikipedia.org/wiki/Sulfonehttp://en.wikipedia.org/wiki/Sulfonehttp://en.wikipedia.org/wiki/Aldehydeshttp://en.wikipedia.org/wiki/Aldehydeshttp://en.wikipedia.org/wiki/Aldehydeshttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Sodium_amalgamhttp://en.wikipedia.org/wiki/Sodium_amalgamhttp://en.wikipedia.org/wiki/Sodium_amalgamhttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Kocienski1978http://en.wikipedia.org/wiki/Julia_olefination#endnote_Kocienski1978http://en.wikipedia.org/wiki/Samarium(II)_iodidehttp://en.wikipedia.org/wiki/Samarium(II)_iodidehttp://en.wikipedia.org/wiki/Samarium(II)_iodidehttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Keck1995http://en.wikipedia.org/wiki/Julia_olefination#endnote_Keck1995http://en.wikipedia.org/wiki/Julia_olefination#endnote_Keck1995http://en.wikipedia.org/wiki/Marc_Juliahttp://en.wikipedia.org/wiki/Marc_Juliahttp://en.wikipedia.org/wiki/Marc_Juliahttp://en.wikipedia.org/wiki/Acetylhttp://en.wikipedia.org/wiki/Acetylhttp://en.wikipedia.org/wiki/Acetylhttp://en.wikipedia.org/wiki/Benzoylhttp://en.wikipedia.org/wiki/Benzoylhttp://en.wikipedia.org/wiki/Benzoylhttp://en.wikipedia.org/wiki/Acetic_anhydridehttp://en.wikipedia.org/wiki/Acetic_anhydridehttp://en.wikipedia.org/wiki/Acetic_anhydridehttp://en.wikipedia.org/wiki/Benzoyl_chloridehttp://en.wikipedia.org/wiki/Benzoyl_chloridehttp://en.wikipedia.org/wiki/Benzoyl_chloridehttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Kocienski1985http://en.wikipedia.org/wiki/Julia_olefination#endnote_Kocienski1985http://en.wikipedia.org/wiki/Julia_olefination#endnote_Kocienski1985http://en.wikipedia.org/wiki/File:Juila_Olefination_Scheme.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismC.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismB.pnghttp://en.wikipedia.org/wiki/File:Juila_Olefination_Scheme.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismC.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismB.pnghttp://en.wikipedia.org/wiki/File:Juila_Olefination_Scheme.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismC.pnghttp://en.wikipedia.org/wiki/File:Bamford-Stevens_MechanismB.pnghttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Kocienski1985http://en.wikipedia.org/wiki/Julia_olefination#endnote_Kocienski1985http://en.wikipedia.org/wiki/Benzoyl_chloridehttp://en.wikipedia.org/wiki/Acetic_anhydridehttp://en.wikipedia.org/wiki/Benzoylhttp://en.wikipedia.org/wiki/Acetylhttp://en.wikipedia.org/wiki/Marc_Juliahttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Keck1995http://en.wikipedia.org/wiki/Samarium(II)_iodidehttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Kocienski1978http://en.wikipedia.org/wiki/Sodium_amalgamhttp://en.wikipedia.org/wiki/Sodium_amalgamhttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Aldehydeshttp://en.wikipedia.org/wiki/Sulfonehttp://en.wikipedia.org/wiki/Phenylhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Chemical_reaction -
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The initial steps are straightforward. The phenyl sulfoneanion(2) reacts with an aldehyde to
form thealkoxide3. The alkoxide is functionalized with R3-X to give the stable intermediate 4.
The exact mechanism of the sodium amalgam reduction is unknown but has been shown to
proceed through a vinylic radical species (5).[1]Protonation of the vinylic radical gives the
desired product (6).
The stereochemistry of the alkene (6) is independent of the stereochemistry of the sulfone
intermediate 4. It is thought that the radical intermediates are able to equilibrate so that the morethermodynamically stable trans-olefin is produced most often.
Variations
Heteroaryl sulfones
The replacement of the phenyl sulfones with heteroaryl sulfones greatly alters the reaction
pathway.[6]
The most popular example is thebenzothiazolesulfone.[7]
The reaction of the
benzothiazole sulfone (1) withlithium diisopropylamide(LDA) gives a metallated benzothiazolyl
sulfone, which reacts quickly with aldehydes (or ketones) to give an alkoxides intermediate (2).Unlike the phenyl sulfones, this alkoxide intermediate (2) is unstable and will undergo aSmiles
rearrangement[8]
to give the sulfinate salt 4. The sulfinate salt (4) will spontaneously
eliminatesulfur dioxideandlithiumbenzothiazolone (5) producing the desired alkene (6).
http://en.wikipedia.org/wiki/Anionhttp://en.wikipedia.org/wiki/Anionhttp://en.wikipedia.org/wiki/Anionhttp://en.wikipedia.org/wiki/Alkoxidehttp://en.wikipedia.org/wiki/Alkoxidehttp://en.wikipedia.org/wiki/Alkoxidehttp://en.wikipedia.org/wiki/Julia_olefination#cite_note-1http://en.wikipedia.org/wiki/Julia_olefination#cite_note-1http://en.wikipedia.org/wiki/Julia_olefination#cite_note-1http://en.wikipedia.org/wiki/Julia_olefination#endnote_Blakemore2002http://en.wikipedia.org/wiki/Julia_olefination#endnote_Blakemore2002http://en.wikipedia.org/wiki/Julia_olefination#endnote_Blakemore2002http://en.wikipedia.org/wiki/Benzothiazolehttp://en.wikipedia.org/wiki/Benzothiazolehttp://en.wikipedia.org/wiki/Benzothiazolehttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Baudin1991http://en.wikipedia.org/wiki/Julia_olefination#endnote_Baudin1991http://en.wikipedia.org/wiki/Julia_olefination#endnote_Baudin1991http://en.wikipedia.org/wiki/Lithium_diisopropylamidehttp://en.wikipedia.org/wiki/Lithium_diisopropylamidehttp://en.wikipedia.org/wiki/Lithium_diisopropylamidehttp://en.wikipedia.org/wiki/Smiles_rearrangementhttp://en.wikipedia.org/wiki/Smiles_rearrangementhttp://en.wikipedia.org/wiki/Smiles_rearrangementhttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Truce1970http://en.wikipedia.org/wiki/Julia_olefination#endnote_Truce1970http://en.wikipedia.org/wiki/Julia_olefination#endnote_Truce1970http://en.wikipedia.org/wiki/Sulfur_dioxidehttp://en.wikipedia.org/wiki/Sulfur_dioxidehttp://en.wikipedia.org/wiki/Sulfur_dioxidehttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/File:Juila_Olefination_Mechanism.pnghttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Sulfur_dioxidehttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Truce1970http://en.wikipedia.org/wiki/Smiles_rearrangementhttp://en.wikipedia.org/wiki/Smiles_rearrangementhttp://en.wikipedia.org/wiki/Lithium_diisopropylamidehttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Baudin1991http://en.wikipedia.org/wiki/Benzothiazolehttp://en.wikipedia.org/wiki/Julia_olefination#endnote_Blakemore2002http://en.wikipedia.org/wiki/Julia_olefination#cite_note-1http://en.wikipedia.org/wiki/Alkoxidehttp://en.wikipedia.org/wiki/Anion -
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Since the benzothiazole variation of the Julia olefination does not involve equilibrating
intermediates, the stereochemical outcome is a result of the stereochemistry of the initial
carbonyl addition. As a result, this reaction often generates a mixture of alkene stereoisomers.
Bestmann-ohira reagent:
Introduction
Bestmann-Ohira reagent [(1-diazo-2-oxopropyl)phosphonate] can be prepared by the reaction ofdimethyl-2-oxopropylphosphonate, TosN3[a] orp-acetamidobenzenesulfonyl azide, [b] NaH, t-BuOK or Et3N in benzene and THF. An alternative is the preparation using polymer-supportedsulfonyl azide and t-BuOK in methylenchloride. [c] The Bestmann-Ohiro reagent is widely usedin the conversion of primary alcohols, aldehydes, ketones, and amides into alkynes. Recently, itwas employed in the synthesis of pyrazoles as well as 1,3-oxazoles.
https://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Ahttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Ahttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Ahttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Bhttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Bhttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Bhttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Chttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Chttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Chttp://en.wikipedia.org/wiki/File:Benzothiazole-Julia_Olefination_Mechanism.pnghttp://en.wikipedia.org/wiki/File:Benzothiazole-Julia_Olefination_Mechanism.pnghttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Chttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1Bhttps://www.thieme-connect.de/ejournals/abstract/10.1055/s-0029-1218101#RV29809ST-1A -
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Scheme1
Bestmann modification
OhiraBestmann reagent
IUPAC name[hide]
imethyl (1-diazo-2-oxopropyl)phosphonate
Dimethyl (diazomethyl)phosphonate can be generated in situ from dimethyl-1-diazo-2-
oxopropylphosphonate (also called Bestmann's reagent) by reaction
withmethanolandpotassium carbonate. Reaction of Bestmann's reagent with aldehydes gives
terminal alkynes often in very high yield.[4][5]
http://en.wikipedia.org/wiki/International_Union_of_Pure_and_Applied_Chemistry_nomenclaturehttp://en.wikipedia.org/wiki/International_Union_of_Pure_and_Applied_Chemistry_nomenclaturehttp://en.wikipedia.org/wiki/International_Union_of_Pure_and_Applied_Chemistry_nomenclaturehttp://en.wikipedia.org/wiki/Methanolhttp://en.wikipedia.org/wiki/Methanolhttp://en.wikipedia.org/wiki/Methanolhttp://en.wikipedia.org/wiki/Potassium_carbonatehttp://en.wikipedia.org/wiki/Potassium_carbonatehttp://en.wikipedia.org/wiki/Potassium_carbonatehttp://en.wikipedia.org/wiki/Ohira-Bestmann_reaction#cite_note-muller1996-4http://en.wikipedia.org/wiki/Ohira-Bestmann_reaction#cite_note-muller1996-4http://en.wikipedia.org/wiki/Ohira-Bestmann_reaction#cite_note-muller1996-4http://en.wikipedia.org/wiki/File:Ohira-bestmann_reagent_2d-skeletal.pnghttp://en.wikipedia.org/wiki/File:Ohira-bestmann_reagent_2d-skeletal.pnghttp://en.wikipedia.org/wiki/Ohira-Bestmann_reaction#cite_note-muller1996-4http://en.wikipedia.org/wiki/Ohira-Bestmann_reaction#cite_note-muller1996-4http://en.wikipedia.org/wiki/Potassium_carbonatehttp://en.wikipedia.org/wiki/Methanolhttp://en.wikipedia.org/wiki/International_Union_of_Pure_and_Applied_Chemistry_nomenclaturehttp://en.wikipedia.org/wiki/International_Union_of_Pure_and_Applied_Chemistry_nomenclature -
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The use of the milder potassium carbonate makes this procedure much more compatible with a
wide variety offunctional groups.
Another modification for less reactive aldehydes is made by replacement of potassium
carbonate withcaesium carbonatein MeOH and results in a drastic yield increase.[6]
BartonKellogg reaction
The BartonKellogg reaction is acoupling reactionbetween aketoneand
athioketonethrough adiazointermediate forming analkene.[1][2][3]
This reaction was pioneered byHermann Staudinger[4]
, and the reaction also goes by thename Staudinger type diazo-thioketone coupling.
Reaction mechanism
In thereaction mechanismfor this reaction thediazocompound is a1,3-dipolewhich reacts with
thethioketonein a1,3-dipolar cycloadditionto athiadiazoline. This intermediate is unstable and
through nitrogen gas expulsion and formation of an intermediatethiocarbonyl ylideit forms a
stableepisulfide.Triphenylphosphineopens the three-membered ring and then forms a
sulfaphosphatane in a manner similar to theWittig reaction. In the final step
triphenylphosphinesulfoxide is expulsed liberating thealkene.
http://en.wikipedia.org/wiki/Functional_grouphttp://en.wikipedia.org/wiki/Functional_grouphttp://en.wikipedia.org/wiki/Functional_grouphttp://en.wikipedia.org/wiki/Caesium_carbonatehttp://en.wikipedia.org/wiki/Caesium_carbonatehttp://en.wikipedia.org/wiki/Caesium_carbonatehttp://en.wikipedia.org/wiki/Ohira-Bestmann_reaction#cite_note-6http://en.wikipedia.org/wiki/Ohira-Bestmann_reaction#cite_note-6http://en.wikipedia.org/wiki/Ohira-Bestmann_reaction#cite_note-6http://en.wikipedia.org/wiki/Coupling_reactionhttp://en.wikipedia.org/wiki/Coupling_reactionhttp://en.wikipedia.org/wiki/Coupling_reactionhttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_Bartonhttp://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_Bartonhttp://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_Kellogg1976http://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_Kellogg1976http://en.wikipedia.org/wiki/Hermann_Staudingerhttp://en.wikipedia.org/wiki/Hermann_Staudingerhttp://en.wikipedia.org/wiki/Hermann_Staudingerhttp://en.wikipedia.org/wiki/Hermann_Staudingerhttp://en.wikipedia.org/wiki/Reaction_mechanismhttp://en.wikipedia.org/wiki/Reaction_mechanismhttp://en.wikipedia.org/wiki/Reaction_mechanismhttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/1,3-dipolehttp://en.wikipedia.org/wiki/1,3-dipolehttp://en.wikipedia.org/wiki/1,3-dipolehttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/1,3-dipolar_cycloadditionhttp://en.wikipedia.org/wiki/1,3-dipolar_cycloadditionhttp://en.wikipedia.org/wiki/1,3-dipolar_cycloadditionhttp://en.wikipedia.org/w/index.php?title=Thiadiazoline&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Thiadiazoline&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Thiadiazoline&action=edit&redlink=1http://en.wikipedia.org/wiki/Thiocarbonyl_ylidehttp://en.wikipedia.org/wiki/Thiocarbonyl_ylidehttp://en.wikipedia.org/wiki/Thiocarbonyl_ylidehttp://en.wikipedia.org/wiki/Episulfidehttp://en.wikipedia.org/wiki/Episulfidehttp://en.wikipedia.org/wiki/Episulfidehttp://en.wikipedia.org/wiki/Triphenylphosphinehttp://en.wikipedia.org/wiki/Triphenylphosphinehttp://en.wikipedia.org/wiki/Triphenylphosphinehttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/File:Barton-Kellogg_reaction.pnghttp://en.wikipedia.org/wiki/File:Bestmann's_Reagent_Scheme.pnghttp://en.wikipedia.org/wiki/File:Barton-Kellogg_reaction.pnghttp://en.wikipedia.org/wiki/File:Bestmann's_Reagent_Scheme.pnghttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Triphenylphosphinehttp://en.wikipedia.org/wiki/Episulfidehttp://en.wikipedia.org/wiki/Thiocarbonyl_ylidehttp://en.wikipedia.org/w/index.php?title=Thiadiazoline&action=edit&redlink=1http://en.wikipedia.org/wiki/1,3-dipolar_cycloadditionhttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/1,3-dipolehttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/Reaction_mechanismhttp://en.wikipedia.org/wiki/Hermann_Staudingerhttp://en.wikipedia.org/wiki/Hermann_Staudingerhttp://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_Kellogg1976http://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_Bartonhttp://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_Bartonhttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Coupling_reactionhttp://en.wikipedia.org/wiki/Ohira-Bestmann_reaction#cite_note-6http://en.wikipedia.org/wiki/Caesium_carbonatehttp://en.wikipedia.org/wiki/Functional_group -
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Scope
The diazo compound can be obtained from aketoneby reaction withhydrazineto
ahydrazonefollowed byoxidation. Many reagents exist for this conversion for examplesilver(I)
oxideand(bis(trifluoroacetoxy)iodo)benzene[5]
. Thethioketonerequired for this reaction can be
obtained from a ketone andphosphorus pentasulfide. Desulfurization of the episulfide can be
accomplished by many phosphines and also bycopperpowder.
The main advantage of this reaction over theMcMurry reactionis the notion that the reaction
can take place with two different ketones. In this regard the diazo-thioketone coupling is a cross-
coupling rather than a homocoupling.
Stevens rearrangement
The Stevens rearrangement inorganic chemistryis anorganic reactionconvertingquaternary
ammonium saltsandsulfonium saltsto the correspondingaminesorsulfidesin presence of a
strongbasein a1,2-rearrangement.[1]
http://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Hydrazinehttp://en.wikipedia.org/wiki/Hydrazinehttp://en.wikipedia.org/wiki/Hydrazinehttp://en.wikipedia.org/wiki/Hydrazonehttp://en.wikipedia.org/wiki/Hydrazonehttp://en.wikipedia.org/wiki/Hydrazonehttp://en.wikipedia.org/wiki/Organic_oxidationhttp://en.wikipedia.org/wiki/Organic_oxidationhttp://en.wikipedia.org/wiki/Organic_oxidationhttp://en.wikipedia.org/wiki/Silver(I)_oxidehttp://en.wikipedia.org/wiki/Silver(I)_oxidehttp://en.wikipedia.org/wiki/Silver(I)_oxidehttp://en.wikipedia.org/wiki/Silver(I)_oxidehttp://en.wikipedia.org/wiki/(bis(trifluoroacetoxy)iodo)benzenehttp://en.wikipedia.org/wiki/(bis(trifluoroacetoxy)iodo)benzenehttp://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_terWielhttp://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_terWielhttp://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_terWielhttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/Phosphorus_pentasulfidehttp://en.wikipedia.org/wiki/Phosphorus_pentasulfidehttp://en.wikipedia.org/wiki/Phosphorus_pentasulfidehttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/McMurry_reactionhttp://en.wikipedia.org/wiki/McMurry_reactionhttp://en.wikipedia.org/wiki/McMurry_reactionhttp://en.wikipedia.org/wiki/Organic_chemistryhttp://en.wikipedia.org/wiki/Organic_chemistryhttp://en.wikipedia.org/wiki/Organic_chemistryhttp://en.wikipedia.org/wiki/Organic_reactionhttp://en.wikipedia.org/wiki/Organic_reactionhttp://en.wikipedia.org/wiki/Organic_reactionhttp://en.wikipedia.org/wiki/Quaternary_ammonium_salthttp://en.wikipedia.org/wiki/Quaternary_ammonium_salthttp://en.wikipedia.org/wiki/Quaternary_ammonium_salthttp://en.wikipedia.org/wiki/Quaternary_ammonium_salthttp://en.wikipedia.org/wiki/Sulfonium_salthttp://en.wikipedia.org/wiki/Sulfonium_salthttp://en.wikipedia.org/wiki/Sulfonium_salthttp://en.wikipedia.org/wiki/Aminehttp://en.wikipedia.org/wiki/Aminehttp://en.wikipedia.org/wiki/Aminehttp://en.wikipedia.org/wiki/Sulfidehttp://en.wikipedia.org/wiki/Sulfidehttp://en.wikipedia.org/wiki/Sulfidehttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/1,2-rearrangementhttp://en.wikipedia.org/wiki/1,2-rearrangementhttp://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-Pine-1http://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-Pine-1http://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-Pine-1http://en.wikipedia.org/wiki/File:Barton-Kellogg_reaction_example.svghttp://en.wikipedia.org/wiki/File:Barton-Kellogg_reaction_mechanism.svghttp://en.wikipedia.org/wiki/File:Barton-Kellogg_reaction_example.svghttp://en.wikipedia.org/wiki/File:Barton-Kellogg_reaction_mechanism.svghttp://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-Pine-1http://en.wikipedia.org/wiki/1,2-rearrangementhttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Sulfidehttp://en.wikipedia.org/wiki/Aminehttp://en.wikipedia.org/wiki/Sulfonium_salthttp://en.wikipedia.org/wiki/Quaternary_ammonium_salthttp://en.wikipedia.org/wiki/Quaternary_ammonium_salthttp://en.wikipedia.org/wiki/Organic_reactionhttp://en.wikipedia.org/wiki/Organic_chemistryhttp://en.wikipedia.org/wiki/McMurry_reactionhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Phosphorus_pentasulfidehttp://en.wikipedia.org/wiki/Thioketonehttp://en.wikipedia.org/wiki/Barton%E2%80%93Kellogg_reaction#endnote_terWielhttp://en.wikipedia.org/wiki/(bis(trifluoroacetoxy)iodo)benzenehttp://en.wikipedia.org/wiki/Silver(I)_oxidehttp://en.wikipedia.org/wiki/Silver(I)_oxidehttp://en.wikipedia.org/wiki/Organic_oxidationhttp://en.wikipedia.org/wiki/Hydrazonehttp://en.wikipedia.org/wiki/Hydrazinehttp://en.wikipedia.org/wiki/Ketone -
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The reactants can be obtained byalkylationof the corresponding amines and sulfides.
ThesubstituentR next the aminemethylene bridgeis anelectron-withdrawing group.
The original 1928 publication by T.S. Stevens[2]concerned the reaction of1-phenyl-2- (N, N-
dimethyl) ethanone withbenzyl bromideto the ammonium salt followed by the rearrangement
reaction withsodium hydroxidein water to the rearranged amine.
A 1932 publication[3]described the corresponding sulfur reaction.
Reaction mechanism
The reaction mechanism of the Stevens rearrangement is one of the most controversial reaction
mechanism in organic chemistry.[4]
Key in thereaction mechanism[5][6]
for the Stevens
rearrangement (explained for the nitrogen reaction) is the formation of
anylideafterdeprotonationof the ammonium salt by a strong base. Deprotonation is aided by
electron-withdrawing properties of substituent R. Several reaction modes exist for the actual
rearrangement reaction.
Aconcerted reactionrequires anantarafacialreaction mode but since the migrating group
displaysretention of configurationthis mechanism is unlikely.
In an alternative reaction mechanism the NC bond of the leaving group ishomolyticallycleaved
to form a di-radical pair (3a). In order to explain the observed retention of configuration, the
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presence of asolvent cageis invoked. Another possibility is the formation of a cation-anion pair
(3b), also in a solvent cage. Recently the elimination recombination coupling mechanism opens
a new approach to understand the formation of normal and abnormal product in the stevens
rearrangement[7]
Scope
Competing reactions are theSommelet-Hauser rearrangementand theHofmann elimination.
In one application a double-Stevens rearrangement expands acyclophanering.[8]
The ylide is
preparedin situby reaction of thediazocompound ethyl diazomalonate with asulfidecatalyzed
by dirhodium tetraacetate inrefluxingxylene.
http://en.wikipedia.org/wiki/Solvent_cagehttp://en.wikipedia.org/wiki/Solvent_cagehttp://en.wikipedia.org/wiki/Solvent_cagehttp://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-7http://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-7http://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-7http://en.wikipedia.org/wiki/Sommelet-Hauser_rearrangementhttp://en.wikipedia.org/wiki/Sommelet-Hauser_rearrangementhttp://en.wikipedia.org/wiki/Sommelet-Hauser_rearrangementhttp://en.wikipedia.org/wiki/Hofmann_eliminationhttp://en.wikipedia.org/wiki/Hofmann_eliminationhttp://en.wikipedia.org/wiki/Hofmann_eliminationhttp://en.wikipedia.org/wiki/Cyclophanehttp://en.wikipedia.org/wiki/Cyclophanehttp://en.wikipedia.org/wiki/Cyclophanehttp://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-8http://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-8http://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-8http://en.wikipedia.org/wiki/In_situhttp://en.wikipedia.org/wiki/In_situhttp://en.wikipedia.org/wiki/In_situhttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/Sulfidehttp://en.wikipedia.org/wiki/Sulfidehttp://en.wikipedia.org/wiki/Sulfidehttp://en.wikipedia.org/wiki/Refluxhttp://en.wikipedia.org/wiki/Refluxhttp://en.wikipedia.org/wiki/Xylenehttp://en.wikipedia.org/wiki/Xylenehttp://en.wikipedia.org/wiki/Xylenehttp://en.wikipedia.org/wiki/File:Stevens_mechanism.pnghttp://en.wikipedia.org/wiki/Xylenehttp://en.wikipedia.org/wiki/Refluxhttp://en.wikipedia.org/wiki/Sulfidehttp://en.wikipedia.org/wiki/Diazohttp://en.wikipedia.org/wiki/In_situhttp://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-8http://en.wikipedia.org/wiki/Cyclophanehttp://en.wikipedia.org/wiki/Hofmann_eliminationhttp://en.wikipedia.org/wiki/Sommelet-Hauser_rearrangementhttp://en.wikipedia.org/wiki/Stevens_rearrangement#cite_note-7http://en.wikipedia.org/wiki/Solvent_cage -
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HornerWadsworthEmmons reaction(Redirected fromWittig-Horner reaction)
The HornerWadsworthEmmons reaction (orHWE reaction) is thechemical reactionof
stabilizedphosphonatecarbanionswithaldehydes(orketones) to produce predominantly E-
alkenes.[1]
In 1958,Leopold Hornerpublished a modifiedWittig reactionusing phosphonate-stabilized
carbanions.[2][3]
William S. WadsworthandWilliam D. Emmonsfurther defined the reaction.[4][5]
In contrast tophosphonium ylidesused in theWittig reaction, phosphonate-stabilized carbanions
are morenucleophilicbut less basic. Likewise, phosphonate-stabilized carbanions can be
http://en.wikipedia.org/w/index.php?title=Wittig-Horner_reaction&redirect=nohttp://en.wikipedia.org/w/index.php?title=Wittig-Horner_reaction&redirect=nohttp://en.wikipedia.org/w/index.php?title=Wittig-Horner_reaction&redirect=nohttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Phosphonatehttp://en.wikipedia.org/wiki/Phosphonatehttp://en.wikipedia.org/wiki/Carbanionhttp://en.wikipedia.org/wiki/Carbanionhttp://en.wikipedia.org/wiki/Carbanionhttp://en.wikipedia.org/wiki/Aldehydehttp://en.wikipedia.org/wiki/Aldehydehttp://en.wikipedia.org/wiki/Aldehydehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-1http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-1http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-1http://en.wikipedia.org/wiki/Leopold_Hornerhttp://en.wikipedia.org/wiki/Leopold_Hornerhttp://en.wikipedia.org/wiki/Leopold_Hornerhttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-2http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-2http://en.wikipedia.org/w/index.php?title=William_S._Wadsworth&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=William_S._Wadsworth&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=William_S._Wadsworth&action=edit&redlink=1http://en.wikipedia.org/wiki/William_D._Emmonshttp://en.wikipedia.org/wiki/William_D._Emmonshttp://en.wikipedia.org/wiki/William_D._Emmonshttp://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-4http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-4http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-4http://en.wikipedia.org/wiki/Phosphonium_ylidehttp://en.wikipedia.org/wiki/Phosphonium_ylidehttp://en.wikipedia.org/wiki/Phosphonium_ylidehttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Nucleophilichttp://en.wikipedia.org/wiki/Nucleophilichttp://en.wikipedia.org/wiki/Nucleophilichttp://en.wikipedia.org/wiki/File:Horner-Wadsworth-Emmons_Reaction_Example.pnghttp://en.wikipedia.org/wiki/File:Stevens_rearrangement_applied.pnghttp://en.wikipedia.org/wiki/File:Horner-Wadsworth-Emmons_Reaction_Example.pnghttp://en.wikipedia.org/wiki/File:Stevens_rearrangement_applied.pnghttp://en.wikipedia.org/wiki/Nucleophilichttp://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Phosphonium_ylidehttp://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-4http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-4http://en.wikipedia.org/wiki/William_D._Emmonshttp://en.wikipedia.org/w/index.php?title=William_S._Wadsworth&action=edit&redlink=1http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-2http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-2http://en.wikipedia.org/wiki/Wittig_reactionhttp://en.wikipedia.org/wiki/Leopold_Hornerhttp://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-1http://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Ketonehttp://en.wikipedia.org/wiki/Aldehydehttp://en.wikipedia.org/wiki/Carbanionhttp://en.wikipedia.org/wiki/Phosphonatehttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/w/index.php?title=Wittig-Horner_reaction&redirect=no -
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alkylated. Unlike phosphonium ylides, the dialkylphosphate salt byproduct is easily removed
byaqueousextraction.
Several reviews have been published.
Reaction mechanism
The HornerWadsworthEmmons reaction begins with thedeprotonationof thephosphonateto
give the phosphonatecarbanion1.Nucleophilic additionof the carbanion onto the aldehyde 2
(or ketone) producing 3a or 3b is therate-limiting step.[10]If R2=H, then intermediates 3a and 4a
and intermediates 3b and 4b can interconvert with each other.[11]The finaleliminationof 4a and
4b yield E-alkene 5 and Z-alkene 6.
The ratio of alkeneisomers5 and 6 is dependent upon thestereochemicaloutcome of the initial
carbanion addition and upon the ability of the intermediates toequilibrate.
Theelectron-withdrawing group(EWG) alpha to the phosphonate is necessary for the final
elimination to occur. In the absence of an electron-withdrawing group, the final product is the -
hydroxyphosphonate 3a and 3b.[12]However, these -hydroxyphosphonates can be transformed
toalkenesby reaction withdiisopropylcarbodiimide.
Stereoselectivity
The HornerWadsworthEmmons reaction favours the formation of E-alkenes. In general, the
more equilibration amongst intermediates, the higher the selectivity for E-alkene formation.
http://en.wikipedia.org/wiki/Aqueoushttp://en.wikipedia.org/wiki/Aqueoushttp://en.wikipedia.org/wiki/Liquid-liquid_extractionhttp://en.wikipedia.org/wiki/Liquid-liquid_extractionhttp://en.wikipedia.org/wiki/Liquid-liquid_extractionhttp://en.wikipedia.org/wiki/Deprotonationhttp://en.wikipedia.org/wiki/Deprotonationhttp://en.wikipedia.org/wiki/Deprotonationhttp://en.wikipedia.org/wiki/Phosphonatehttp://en.wikipedia.org/wiki/Phosphonatehttp://en.wikipedia.org/wiki/Phosphonatehttp://en.wikipedia.org/wiki/Carbanionhttp://en.wikipedia.org/wiki/Carbanionhttp://en.wikipedia.org/wiki/Carbanionhttp://en.wikipedia.org/wiki/Nucleophilic_additionhttp://en.wikipedia.org/wiki/Nucleophilic_additionhttp://en.wikipedia.org/wiki/Nucleophilic_additionhttp://en.wikipedia.org/wiki/Rate-limiting_stephttp://en.wikipedia.org/wiki/Rate-limiting_stephttp://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-10http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-10http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-10http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-11http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-11http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-11http://en.wikipedia.org/wiki/Elimination_reactionhttp://en.wikipedia.org/wiki/Elimination_reactionhttp://en.wikipedia.org/wiki/Elimination_reactionhttp://en.wikipedia.org/wiki/Isomerhttp://en.wikipedia.org/wiki/Isomerhttp://en.wikipedia.org/wiki/Isomerhttp://en.wikipedia.org/wiki/Stereochemicalhttp://en.wikipedia.org/wiki/Stereochemicalhttp://en.wikipedia.org/wiki/Stereochemicalhttp://en.wikipedia.org/wiki/Chemical_equilibriumhttp://en.wikipedia.org/wiki/Chemical_equilibriumhttp://en.wikipedia.org/wiki/Chemical_equilibriumhttp://en.wikipedia.org/wiki/Electron-withdrawing_grouphttp://en.wikipedia.org/wiki/Electron-withdrawing_grouphttp://en.wikipedia.org/wiki/Electron-withdrawing_grouphttp://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-12http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-12http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-12http://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Diisopropylcarbodiimidehttp://en.wikipedia.org/wiki/Diisopropylcarbodiimidehttp://en.wikipedia.org/wiki/Diisopropylcarbodiimidehttp://en.wikipedia.org/wiki/File:Horner-Wadsworth-Emmons_Mechanism.pnghttp://en.wikipedia.org/wiki/Diisopropylcarbodiimidehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-12http://en.wikipedia.org/wiki/Electron-withdrawing_grouphttp://en.wikipedia.org/wiki/Chemical_equilibriumhttp://en.wikipedia.org/wiki/Stereochemicalhttp://en.wikipedia.org/wiki/Isomerhttp://en.wikipedia.org/wiki/Elimination_reactionhttp://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-11http://en.wikipedia.org/wiki/Wittig-Horner_reaction#cite_note-10http://en.wikipedia.org/wiki/Rate-limiting_stephttp://en.wikipedia.org/wiki/Nucleophilic_additionhttp://en.wikipedia.org/wiki/Carbanionhttp://en.wikipedia.org/wiki/Phosphonatehttp://en.wikipedia.org/wiki/Deprotonationhttp://en.wikipedia.org/wiki/Liquid-liquid_extractionhttp://en.wikipedia.org/wiki/Aqueous -
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Bibliography:BOOKS:
AHLUWALIA
PS KALSI
ADVANCED ORGANIC CHEMISTRY BY BRUCKNER
NET:
WWW.WIKIPEDIA.COM
GOOGLE.COM
http://www.wikipedia.com/http://www.wikipedia.com/http://www.wikipedia.com/