Abstract
Use of the "bulky proton" containing reagents trimethylsilyl trifluoromethanesulfonate and 1,2-bis[(trimethylsilyl)oxy]ethane to ketalize or acetalize compounds containing two nonconjugated carbonyl groups or one nonconjugated and one α,β-unsaturated carbonyl group provides, with high selectivity, monodioxolanes bearing the ketal or acetal function at the less sterically hindered site. © 1985 American Chemical Society.