Facile preparation of novel nonracemic oxy-substituted cyclopropanone S,S-acetals by gamma-cyclisation of glyceric aldehyde dithioacetal derivatives and studies of their reactivity

Easily available glyceric aldehyde dithioacetals, (R)-1 and (R)-2, are converted via their tosylates, (R)-7a and b, and gamma-elimination into nonracemic oxy-substituted cyclopropanone S,S-acetals, (R)-12 and (R)-13, in the presence of suitable electrophiles for trapping of alkoxide intermediates. Treatment of cyclopropanol (R)-14 with Burgess' reagent causes no 1,2-elimination, but a remarkable S-N etherification with retention of configuration.