Addition reactions of aldehydes to lithium enolates of 1,3-dioxolan-4-ones: a configurational reassessment

The results for the addition reactions of chiral lithium (2S)-enolates of 1,3-dioxolan-4-ones to aldehydes and to acetophenone, yielding the corresponding dioxolanone alcohols have been revised. The results reported herein differ from those reported in the literature, both in product distribution and in the stereochemical assignment of the products. In fact, in several cases no stereocontrol was observed at the C5 carbon atom of the lithium enolate. The (2S,5R,1'S)/(2S,5R,1'R) stereochemistry was also reassessed for several dioxolanone alcohols. The major conformers are considered to have an intramolecular hydrogen-bonded five-membered ring structure instead of the six-membered ring structure previously suggested for cyclic dioxolanone alcohols.