Enzymatic resolution of 1,1-dimethoxybut-3-en-2-ol and 1,1-dimethoxypent-4-en-2-ol, α-hydroxyaldehyde precursors for aldol-type reactions

Hydroxyacetals 2 and 3 were resolved by acylation with vinyl acetate in the presence of lipases in organic media. The reverse reaction, the enzymatic hydrolysis of the corresponding acetates, was also highly stereoselective and provided the opposite enantiomers.

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(2S)-1,1-Dimethoxybut-3-en-2-olC6H12O3Ee = 93% (chiral GC)[α]D22=-32.7 (c 1.28, CHCl3)Source of chirality: enzymatic kinetic resolutionAbsolute configuration: 2S

(1R)-1-(Dimethoxymethyl)prop-2-enyl acetateC8H14O4Ee = 95% (chiral GC)[α]D22=+27.5 (c 1.23, CHCl3)Source of chirality: enzymatic kinetic resolutionAbsolute configuration: 1R

(2R)-1,1-Dimethoxypent-4-en-2-olC7H14O3Ee = 98% (chiral GC)[α]D22=+8.8 (c 1.17, CHCl3)Source of chirality: enzymatic kinetic resolutionAbsolute configuration: 2R

(1S)-1-(Dimethoxymethyl)but-3-enyl acetateC9H16O4Ee = 96% (chiral GC)[α]D22=+14.4 (c 0.98, CHCl3)Source of chirality: enzymatic kinetic resolutionAbsolute configuration: (1S)