Asymmetric Dihydroxylations of Enynes with a Trisubstituted C═C Bond. An Unprecedented Route to γ-Lactone Building Blocks with a Quaternary Stereocenter
comprehensive set of hydroxylactone building blocks (4R,5R)-, (4R,5S)-, (4S,5R)-, and (4S,5S)-5a, Sharpless asymmetric dihydroxylations of allylicchlorides (E)- and (Z)-9 were performed. They delivered the four stereoisomers of diol 10 with up to 92% ee and absolute configurations, which were proven to be in accordance with the Sharpless mnemonic.