rhenium-catalyzed didehydroxylation of vicinal diols to alkenes … · 2011. 11. 8. ·...

Rhenium-Catalyzed Didehydroxylation of Vicinal Diols to Alkenes Using a Simple Alcohol as a Reducing Agent

Elena Arceo, Jonathan A. Ellman, Robert G. BergmanJ. Am. Chem. Soc. 2010, 132, ASAP

On the Absolute Configurational Stability of Bromonium and Chloronium Ions

Scott E. Denmark, Matthew T. Burk, Andrew J. HooverJ. Am. Chem. Soc. 2010, 132, 1232-1233

Antoinette NibbsShort Literature Presentation

23 August 2010

R

OH

OH

RR

R

RR R

RX

development of new methods for production of reduced oxygen-content from renewable biomass resources

Deoxygenation of Biomass Polyols

Arceo, E; Marsden, P.; Bergman, R. G.; Ellman, J. A. Chem. Commun. 2009, 3357

development of new methods for production of reduced oxygen-content from renewable biomass resources

sustainable production of transportation fuels from biomass in an integrated biomass production-conversion system

Huber, G. W.; Iborra, S.; Corma, A. Chem. Rev. 2006, 106, 4044-4098

single-flask, solvent-free deoxygenation procedure to convert glycerol into allyl alcohol (polymer, 3-hydroxyproionic acid)

Prior Art

OH

OH

OO

OO

MeMe

MeMe

Cp*ReO3, PPh3

C6H5Cl, 125 °C, 80h

OO

OO

MeMe

MeMe

86% bdc

Cook, G. C. and Andrews, M. A. J. Am. Chem. Soc. 1996, 118, 9448-9449

O

R'

OH

R'R

HOor

MeReO3 (5-10 mol %)

H2 (80-300 psi), 150 °C, THF R'R18-96% yield

Ziegler, J. E.; Zdilla, M. J.; Evans, A. J.; Abu-Omar, M. M. Inorg. Chem. 2009, 48, 9998-10000

4-60% yieldO

R R'

OH

R'R

HOor

MeReO3 or NaReO4 (5-10 mol %)

150 °C, solvent, Na2SO3R'R

Vkuturi, S.; Chapman, G.; Ahmad, I.; Nicholas, K. Inorg. Chem. 2010, 49, 4744

Preliminary Experiments

reaction characteristics

•aliquots at intermediate conversion contained the vicinal diketone

•at the early stages, as amount of olefin increased the amount of diketone increased

•upon complete conversion of olefin, depletion and eventual disappearance of diketone

disproportionation reaction?

OH

OH

MeMe

(4S*,4S*)-octane-4,5-diol

Re2(CO)10 (2.5 mol %)

180 °C, air3.5 h

(50%)

MeMe

RR

O

O

H2O

Disproportionation Reaction

species simultaneously oxidized and reduced to form two different products

•Cannizzaro reaction

•Tishchenko reaction

OHR

OHR

OR

OR oxidant

RRreductant

Preliminary Experiments, Part 2

HO(CH2)11CH3

OH

1,2-tetradenanediol

Re2(CO)10 (2.5 mol %)

180 °C, air3.5 h

49%

(CH2)11CH3H2O

HOR

OH

Re2(CO)10 (2.5 mol %)

< 170 °C, airrecovered diol

Re2(CO)10 (2.5 mol %)

180 °C, N2

recovered diol

OHR

OHR

OR

OR oxidant

RRreductant

add external alcohol to avoid competing diol oxidation

entry catalyst reductant (mL) temp (°C) time (h) yield (%)

12345

Re2(CO)10 Re2(CO)10 Re2(CO)10 Re2(CO)10 BrRe(CO)5

5-nonanol (4)3-octanol (4)3-octanol (5)2-octanol (4)3-octanol (4.5)

180170170170170

3.5 4 4 3.5 4

83 82 (82)

83 74

84 (85)

OHMe Me

OHMe

Me Me

OHMe

5-nonanol 3-octanol 2-octanol

Reducing Competing Diol Oxidation

R' R''

OH

R' R''

O

use of 9-13 equiv of alcohol afforded complete product in 3.5-4 halcohols generated 1-1.5 equiv of ketone

Cp*Re(CO)3 did not show any activity; BrRe(CO)5 exhibited similar activity

HO(CH2)11CH3

OH Re2(CO)10 or BrRe(CO)5 (2.5 mol %)

temp, air(CH2)11CH3

H2O

Prior Art

OH

OH

OO

OO

MeMe

MeMe

Cp*ReO3, PPh3

C6H5Cl, 125 °C, 80h

OO

OO

MeMe

MeMe

86% bdc

Cook, G. C. and Andrews, M. A. J. Am. Chem. Soc. 1996, 118, 9448-9449

O

R'

OH

R'R

HOor

MeReO3 (5-10 mol %)

H2 (80-300 psi), 150 °C, THF R'R18-96% yield

Ziegler, J. E.; Zdilla, M. J.; Evans, A. J.; Abu-Omar, M. M. Inorg. Chem. 2009, 48, 9998-10000

4-60% yieldO

R R'

OH

R'R

HOor

MeReO3 or NaReO4 (5-10 mol %)

150 °C, solvent, Na2SO3R'R

Vkuturi, S.; Chapman, G.; Ahmad, I.; Nicholas, K. Inorg. Chem. 2010, 49, 4744

Internal Diols

OH

OH(72%)

BrRe(CO)5 (2.5 mol %)

3-octanol, 170 °C, air2 h

trans stereoisomer did not react in the presence of alcohol or solvent-free conditions

OH

(3R*,4R*)-decane-3,4-diol

Re2(CO)10 (2.5 mol %)


(82%)

MeOH

(CH2)4CH3 (CH2)4CH3Me

Letʼs Make It Better

decrease the reaction temperature by use of an additive

acidsTsOH or H2SO4 shortened the reaction times

lower reaction temperaturelower catalyst loading

baseslonger reaction times

total obstruction of activity

sugar polyols (or sugar alcohol)

glycerolerythritolarabitolxylitolmannitolsorbitol

HOOH

OH

OHOH O

HO

OHOH

HO

arabitol arabinose

OH


Re2(CO)10 (2.5 mol %)


(82%)

MeOH


Optimized Results

1 : 0.025 : 10 ratio of diol, catalyst, and 3-octanol

entry cat (mol %) alcohol (mL) temp (°C) time (h) yield (%)

1234567

2.5 2.5 1 1 1 2.5 1.25

4433555

155 155 170 155 155 155155

5 2.5 16 1.5 1.8 2 2

0 74 (76)

4677

87 (83)82 (85)

79

acid (mol %)

-T (5)-T (2)T (2)S (2)S (2)

HO(CH2)11CH3

OH

1,2-tetradenanediol

Re2(CO)10 (2.5 mol %)

TsOH (T) or H2SO4 (S)

3-octanol, temp(CH2)11CH3

reaction did not proceed in the presence of acid and absence of catalyst

Applications

(62% NMR yield)55% isolated yield>94 mol % pure

meso-erythritol

HOOH

OHOH

Re2(CO)10 (1.5 mol %)

TsOH (1.7 mol %)160 °C, 12 h3-octanol, air

O

O

HO OH

Huber, G. W.; Iborra, S.; Corma, A. Chem. Rev. 2006, 106, 4044-4098

Reaction Mechanism

"In contrast to the simplicity of the reaction methodology, the mechanism of the reaction is still unknown."

temperature and oxygen dependence suggests an oxidized rhenium species as the active catalystand...

diol has to be capable of achieving cis stereochemistryso...

rhenium diolate species

some metal diolates extrude corresponding alkene on thermolysis

affect of acid on catalyst related to assisted olefin extrusion by protonation of a rhenium diolate intermediate

Conclusions

method can be applied to producing unsaturated compounds from other biomass-derived polyols

new catalytic system rhenium-mediated didehydroxylation of vicinal diols (internal or external) using external alcohol as an environmentally friendly reducing agent

(62% NMR yield)55% isolated yield>94 mol % pure

meso-erythritol

HOOH

OHOH

Re2(CO)10 (1.5 mol %)

TsOH (1.7 mol %)160 °C, 12 h3-octanol, air

O

addition of acid allows for milder reaction conditions (155 °C, up to 2 h reaction time)

OH


Re2(CO)10 (2.5 mol %)


(82%)

MeOH


only a few enantioselective variants

few of those variants require substoichiometric amounts of chiral promoter

Electrophilic Halofunctionalization of Olefins

Kwon, H.; Park, C.; Lee, S.; Youn, J.; Kang, S. Chem. Eur. J. 2008, 14, 1023-1028

Snyder, S. A.; Tang, Z.-Y.; Gupta, R. J. Am. Chem. Soc. 2009, 131, 5744-5745

OHOH

swainsonine

OH

N3

NCS, I2, K2CO3, cat.

PhMe, —78 °C

86%, 90% ee

N

OH OH

OH

HO

IN3

O

N

t-Bu

t-Bu

N

O t-Bu

t-Bu

CrCl

O

O

OH

MOMO O MeMe

BH3·THF, cat.

Cl2, THF, —78 °C

O

O

OH

MOMO O MeMe

ClCl

93%, 87% ee

O

O

OMe

MOMO O

Cl

Me

Me

Me

MeMe

Cl

(—)-napyradiomycin A1

Electrophilic Halofunctionalization of Olefins

Snyder, S. A.; Tang, Z.-Y.; Gupta, R. J. Am. Chem. Soc. 2009, 131, 5744-5745

O

O

OMe

MOMO O

Cl

Me

Me

Me

MeMe

Cl

(—)-napyradiomycin A1

Me

Cl

Cl

OSO3H

Cl

Cl

Cl

Cl

chlorosulpholipid cytotoxin

Nilewski, C.; Geisser, R. W.; Carreira, E. M., Nature 2009, 457, 573-576Bedke, D. K.; Sibuya, G. M.; Pereira, A.; Gerwick, W. H.; Haines, T. H.; Vanderwal, C. D. J. Am. Chem. Soc. 2009, 131, 7570-7572

only a few enantioselective variants

few of those variants require substoichiometric amounts of chiral promoter

bromine exchange between bromonium ions and olefins can be rapid

Neverov, A. A.; Brown, R. S. J. Org. Chem. 1996, 61, 962-968

The paucity of such methods can be ascribed in part to a lack of understanding of the factors that influence the configurational stability of the intermediate halonium ions.

What Do We Know About Them?

Denmark, S. E.; Collins, W. R.; Cullen, M. D. J. Am. Chem. Soc. 2009, 131, 3490-3492

E

R1

H

R1

R SbF6

R2

R2 CD2Cl2

temp R1

R1

E

R2

H

R2

R SbF6

RE = PhSe, n-BuSe

similar to processes for thiiranium and seleniranium ions

enantiopure bromonium ions have been demonstrated to be stable in the absence of olefins

no studies for olefin-to-olefin transfer observation

SO

OO

C10H21

Br

O

OO

OMe

TiCl4

enantiopure

C10H21

BrC10H21

ClBr

enantiopure product

Braddock, D. C.; Hermitage, S. A.; Kwok, L.; Pouwer, R.; Redmond, J. M.; White, A. J. P. Chem. Commun. 2009, 1082-1084

Absolute Configurational Stability of Bromonium Ions

RBr

RRR

RBr

R

establish configurational stability of bromonium and chloronium ions under conditions where racemization could be competitive with intermolecular trapping by nucleophiles

absolute configurational stability of chloronium ions has never been demonstrated under any conditionsrelative configurational stability established in classic studies by Lucas and Winstein

Lucas, H. J.; Gould, C. W., Jr. J. Am. Chem. Soc. 1941, 63, 2541-2551

Winstein, S.; Seymour, D. J. Am. Chem. Soc. 1946, 68, 119-122

Chloronium Ions In Days of Old

generated by anchimerically assisted ionization of enantiomerically enriched, C2 symmetric B-halo sulfonates in strongly ionizing media

• demonstrate bromonium ion formation and trapping in the presence of subsolvent quantities of nucleophiles• provide for degenerate bromine exchange• HFIP as solvent

n-Prn-Pr

OTs

Br

er = 97:3

HCO2Na (13 equiv)

HCO2H, 23 °C(68%)

n-Prn-Pr

OCHO

Br

er: 97:3 100% enantiospecificity

HCO2Na, HCO2H, 23 °C(82%)

(10 equiv)OBnBnO

establish configurational stability of bromonium and chloronium ions under conditions where racemization could be competitive with intermolecular trapping by nucleophiles

enantiospecificity = eeprod / eesm X 100%

Preliminary Experiments

whatʼs the next step?

HFIP strong ionizing solvent, low nucleophilicity

dissolve both nucleophilic salts and significant quantities of the olefin

minor racemization pathway - nucleophilic attack at bromine to generate BrN3

n-Prn-Pr

OTs

Br HFIP, 23 °C n-Prn-Pr

R

Br

Nu

n-Prn-Pr

OAc

Br

NaOAc (2 equiv)79% yield

97:3 er100% es

MeOH (10 equiv) n-Prn-Pr

OMe

Br

80% yield97:3 er

100% es

n-Prn-Pr

N3

Br

n-Bu4NN3 (2 equiv)80% yield

95:5 er96% es

Solvolysis of Enantiomerically Enriched Bromide

n-Prn-Pr

OTs

Br

MOAc

HFIP, 23 °Cn-Pr

n-PrOAc

Brn-Pr

n-Pr


introduction of olefin leads to lower specificity

n-Prn-Pr

OTs

Br

MOAc

HFIP, 23 °Cn-Pr

n-PrOAc

Brn-Pr

n-Pr

increased trapping rate due to less coordinated and more nucleophillic anion


introduction of olefin leads to lower specificity

assuming you can generate and trap chloronium ions enantiospecifically, even in the absence of olefin-to-olefin transfer

Denmark, S. E.; Collins, W. R.; Cullen, M. D. J. Am. Chem. Soc. 2009, 131, 3490-3492

E

R1

H

R1

R SbF6

R2

R2 CD2Cl2

temp R1

R1

E

R2

H

R2

R SbF6

RE = PhSe, n-BuSe

Modulating Olefin-to-Olefin Transfer Rate

HCO2Na, HCO2H, 23 °C(63%)

(10 equiv)OBnBnO

Solvolysis of Enantiomerically Enriched Chloride

n-Prn-Pr

OTf

Cl

er = 98:2dr > 99:1

HCO2Na (13 equiv)

HCO2H, 23 °C(76%)

n-Prn-Pr

OCHO

Cl

er = 98:2dr = 98:2

100% enantiospecificity

n-Prn-Pr

OTf

Cl

dr = 99:1

HCO2Na (13 equiv)

HCO2H, 23 °C(58%)

n-Prn-Pr

OCHO

Cl

dr = 97:3

NaOAc gave complex mixtures of products

low chemical stability of 1,2-dialkylchloronium ions dictates the use of more reactive nucleophile to trap them before low energy decomposition pathways can intervene

n-Prn-Pr

OTf

Cl HFIP/CH2Cl2 1:1, 23 °Cn-Pr

n-PrOR

Cl

Nu

n-Prn-Pr

R Nu olefin (equiv) yield (%) er e.s. (%)AcAcAcMe

n-Bu4NOAc n-Bu4NOAc n-Bu4NOAc MeOH

00.251.00

32394342

98:2 98:2 98:2 98:2

100100100100

Solvolysis of Enantiomerically Enriched Chloride

•lesser electronegativity of bromine•olefin-olefin transfer proceeds via nucleophilic attack by olefin at bromine•favored by greater positive charge on bromine

chemical stability stereochemical stability

inverse relationship

degree to which positive charge is located on the halogens in the halonium ion

n-Prn-Pr

Cl n-Prn-Pr

Br

•greater electronegativity of chlorine •less positive charge on chlorine•more positive charge on carbon•increased propensity toward processes characteristic of carbocations

Stability of Halonium Ions

demonstrated first enantioselective generation and trapping of chloronium ions

enantiospecific generation and trapping of bromonium ions

racemization of bromonium ions via olefin-to-olefin tranfer is competive with intermolecular capture by anionic nucleophiles

relative rates do not exclude possibility of a catalytic, enantioselective bromination process, but present an obstacle that must be surmounted by any successful catalyst system

n-Prn-Pr

OTs

Br

er = 97:3

HCO2Na (13 equiv)

HCO2H, 23 °C(68%)

n-Prn-Pr

OCHO

Br

er: 97:3 100% enantiospecificity

Conclusions

n-Prn-Pr

OTs

Br HFIP, 23 °Cn-Pr

n-PrOAc

Br

79% yield97:3 er

100% esNaOAc

n-Prn-Pr

OTf

Cl

er = 98:2dr > 99:1

HCO2Na (13 equiv)

HCO2H, 23 °C(76%)

n-Prn-Pr

OCHO

Cl

er = 98:2dr = 98:2

100% enantiospecificity

rhenium-catalyzed didehydroxylation of vicinal diols to alkenes … · 2011. 11. 8. ·...

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