Organocatalytic asymmetric 1,4-addition of organoboronic acids to γ-hydroxy α,β-unsaturated aldehyde: facile synthesis of chiral β-substituted γ-lactones

Catalytic asymmetric 1,4-addition of arylvinyl- and arylboronic acids to a γ-hydroxy α,β-unsaturated aldehyde, which affords β-substituted γ-lactols, has been established using a diarylprolinol silyl ether as an organocatalyst. The β-substituted γ-lactols have been obtained in good yields and with up to 91% ee, which lead to chiral β-substituted γ-lactones followed by oxidation.