Enantiocomplementary synthesis of functionalized cycloalkenol building blocks using lipase
摘要:
Racemic 2-carbethoxy-2-cyclopenten-1-ol [(+/-)-3a] and racemic 2-carbethoxy-2-cyclohexen-1-ol [(+/-)-3b] afforded the corresponding (R)-acetates [(R)-4a and (R)-4b] leaving the corresponding (S)-alcohols [(S)-3a and (S)-3b] unchanged upon treatment with vinyl acetate in tert-butyl methyl ether in the presence of lipase PS, respectively, while the racemic acetates [(+/-)-4a and (+/-)-4b], derived from racemic precursors, (+/-)-3a and (+/-)-3b, on suspension with lipase in a phosphate buffer solution afforded the corresponding (R)-alcohols [(R)-3a and (R)-3b] leaving the corresponding (S)-acetates [(S)-4a and (S)-4b] unchanged, respectively.
A highly enantioselective proline catalyzed intramolecular Baylis-Hillman reaction of hept-2-enedial is reported. Addition of imidazole to the mixture results in art unusual inversion of enantioselectivity. (c) 2005 Elsevier Ltd. All rights reserved.
Enantiocomplementary synthesis of functionalized cycloalkenol building blocks using lipase
Racemic 2-carbethoxy-2-cyclopenten-1-ol [(+/-)-3a] and racemic 2-carbethoxy-2-cyclohexen-1-ol [(+/-)-3b] afforded the corresponding (R)-acetates [(R)-4a and (R)-4b] leaving the corresponding (S)-alcohols [(S)-3a and (S)-3b] unchanged upon treatment with vinyl acetate in tert-butyl methyl ether in the presence of lipase PS, respectively, while the racemic acetates [(+/-)-4a and (+/-)-4b], derived from racemic precursors, (+/-)-3a and (+/-)-3b, on suspension with lipase in a phosphate buffer solution afforded the corresponding (R)-alcohols [(R)-3a and (R)-3b] leaving the corresponding (S)-acetates [(S)-4a and (S)-4b] unchanged, respectively.