3_04_05 - CO 2 Me CO 2 Me CO 2 H CO 2 Me O O Baker's yeast...

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Massachusetts Institute of Technology Organic Chemistry 5.512 March 4, 2005 Prof. Rick L. Danheiser Strategies for Stereocontrolled Synthesis Thermodynamic Control Kinetic Control Substrate Control Steric Approach Control Stereoelectronic Control Internal Stereodirection Reagent Control Achiral Substrate: enantiotopic face selectivity Achiral Substrate: enantiotopic group selectivity Chiral Substrate: Double Asymmetric Synthesis Dynamic Kinetic Resolution Reagent Control Strategies: Examples of Enantiotopic Group Selectivity Lipase-Based Desymmetrization Reactions OAc OAc PPL MeO 2 C CO 2 Me PLE HO 2 C CO 2 Me 60% 93% NHCO 2 Bn 96%ee NHCO 2 Bn 100%ee OAc OH M. Ohno J. Nokami J. Am. Chem. Soc. 1981 , 103 , 2405 Tetrahedron Lett. 32 , 2409, 1991
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Unformatted text preview: CO 2 Me CO 2 Me CO 2 H CO 2 Me O O Baker's yeast sucrose H 2 O 47-52% 96-98.8% ee PLE 98% 96%ee O OH M. Ohno Tetrahedron Lett. 1984 , 25 , 2557 K. Mori and H. Mori Org. Synth. Coll. Vol. 8 , 312, 1993 Another example of biotransformations in asymmetric synthesis Reagent Control Strategies: Enantiotopic Group Selectivity Coupled to Kinetic Resolution OH 1) HCO 2 Me OH AE BnO 2) RedAl (-)-DIPT Li OBn OBn OBn OBn O S. L. Schreiber 70-80% 1 h 93% ee J. Am. Chem. Soc. 1987 , 109 , 1525 44 h >97% ee >97% de ( [A + ent-A]/[B + ent-B] ) O O B O A O OBn OBn OH ent-B OBn OBn OH OBn OBn OH ent-A OBn OBn OH OH O OBn OBn OH OH O OBn OBn O OBn OBn A OH O OBn OBn OH O OBn OBn OH OH O OBn OBn OBn O OBn ent-A OH O OBn OBn...
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This note was uploaded on 11/27/2011 for the course CHEM 5.43 taught by Professor Timothyf.jamison during the Spring '07 term at MIT.

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3_04_05 - CO 2 Me CO 2 Me CO 2 H CO 2 Me O O Baker's yeast...

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