Use of odorless thiols: Formal asymmetric Michael addition of hydrogen sulfide to alpha-substituted alpha,beta-unsaturated carbonyl compounds

[GRAPHICS] The Michael addition to alpha -substituted alpha,beta -unsaturated esters a nd amides using complex A containing a chiral odorless thiol proceeded dias tereoselectively. The Michael adducts were converted to beta -mercapto este rs and amides via a Wagner-Meerwein rearrangement with boron trifluoride et herate and a thiol exchange reaction using odorless 1-dodecanethiol. This c onversion constitutes a formal asymmetric Michael addition of hydrogen sulf ide to alpha,beta -unsaturated carbonyl compounds using odorless thiols ins tead of the toxic hydrogen sulfide.