Organocatalytic alpha-hydroxymethylation of cyclopentanone with aqueous formaldehyde: easy access to chiral delta-lactones.

Optically active lactones are important synthons in perfume and aroma manufacturing. Therefore, developments of efficient asymmetric syntheses are desired. Organocatalytic asymmetric alpha-hydroxymethylations of cyclopentanone with aqueous formaldehyde have been developed, to furnish the corresponding alpha-(hydroxymethyl)cyclopentanone with high enantioselectivity. Further chemical transformation of alpha-(hydroxymethyl)cyclopentanone gave the key intermediate for jasmine lactone, which is widely found in fruits and flowers.