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Problems AnswersJohannes Walker
19/11/13
Trost, B.M.; J. Am. Chem. Soc., 2012, 134, 1474–1477
Thionium Ion iniCated Medium-‐Sized Ring FormaCon: The Total Synthesis of Asteriscunolide D
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Trost, B.M.; J. Am. Chem. Soc., 2012, 134, 1474–1477
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Asteriscunolide D
Trost, B.M.; J. Am. Chem. Soc., 2012, 134, 1474–1477
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Points to note:1) Use of thionium ions as ‘super-‐carbonyls’2) DMTSF has also shown remarkably chemoselecCve acCvator for the thioketal moiety in some acid sensiCve compounds3) DiastereoselecCve macrocyclisaCon to give usually difficult to form medium-‐sized ring4) StereoselecCve (E) olefin formaCon in final product, in accordance with the Hofmann eliminaCon rule
Trost, B.M.; J. Am. Chem. Soc., 2012, 134, 1474–1477
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Maulide, N.; J. Am. Chem. Soc., 2013, 135, 14968–14971
Electrophilic Rearrangements of Chiral Amides: A Traceless Asymmetric α-‐AllylaCon
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K-‐Selectride:
•Borohydride reducing agent•N-‐ (Sodium) and L-‐ (Lithium) reagents are also available (Sigma)•May be used for stereoselecCve conjugate hydride reducCons and carbonyl 1,2 reducCons due to steric bulk•Also known to reduce imides, lacCms and oxazolines in high yield, hence use here
Corey, E.J.; J. Am. Chem. Soc., 2009, 131, 5746–5747
A Short and Efficient Synthesis of (–)-‐7-‐Methylomuralide, a Potent Proteasome Inhibitor
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Corey, E.J.; J. Am. Chem. Soc., 2009, 131, 5746–5747
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Points to note:1) Use of chiral sulfone as an alternaCve chiral auxiliary
Mulzer, J.; Org. Le5., 2010, 12, 272–275
From Silphinenes to Penifulvins: A BiomimeCc Approach to Penifulvins B and C
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Zografos, A.; Org. Le5., 2013, 15, 152–155
Non-‐natural Elemane as the “Stepping Stone” for the synthesis of Germacrane and Guaiane Sesquiterpenes
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Things to note:1) Rearrangement to give usually difficult to form medium-‐sized ring2) Change in 10-‐membered ring conformaCon between Cope and ene reacCons