Non-PTC-Catalyzed Enantioselective Michael Addition Reactions

Deng also successfully applied the C6 —OH catalysts 64a,b to the asymmetric tandem conjugate addition-protonation reactions of the a-cyanoketones or 

70a-d were obtained using 64b ent-70a-c were obtained using 64a 

In 2006, Wang and coworkers reported the asymmetric Michael addition of a broad spectrum of nucleophiles to chalcones (25) using the thiourea catalyst 81a [24], 

Wang and coworkers found that the quinine-derived thiourea catalyst 81b (1 mol%) was also highly reactive and enantioselective for the tandem thio-Michael-aldol reaction of various 2-mercaptobenzaldehydes (103) with a,P-unsaturated oxazolidi-nones (104), furnishing benzothiopyranes (105) with three stereogenic centers in 

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