Asymmetric synthesis of all 8 stereoisomers of α-methyl homoallylic alcohols derived by crotyl addition onto bis(hydroxymethyl)acetaldehydes (BHYMA*)
摘要:
The asymmetric synthesis of epimeric alpha-methyl homoallylic alcohols 4 and 7 has been realized respectively through chelation-controlled addition of crotyltributyltin to asymmetrized bis(hydroxymethyl)acetaldehydes (BHYMA*) 3, and via chelation-controlled reduction of ketones 8. Due to the stereochemical flexibility of the C-5 chiral centre and to the enantiodivergent preparation of both enantiomers of 3, all 8 isomers of these crotylation products become accessible, starting from an unique precursor 1.
Highly Versatile Stereoselective Synthesis of All Eight Stereoisomers of Branched-Chain Triols Starting from Asymmetrized Bis(hydroxymethyl)acetaldehydes (BHYMA)
All possible stereoisomers of triols of general formula 5 (R(1) allyl, R(2) = Me or allyl) have been synthesized stereoselectively starting from asymmetrized bis(hydroxymethyl)acetaldehyde (BHY-MA*), a novel chiral building block prepared through a chemoenzymatic methodology. This goal was realized through a sequence of protecting group-controlled nucleophilic additions and/or reductions performed on two side arms of this versatile building block.