Thiourea stereoselective cinchona alkaloid

In 2010, Zhong and co-workers [32] tried a similar approach using nitrotyrenes and cyclic ketoesters. The reaction occurs through a Michael-Henry cascade reaction catalyzed by bifunctional thiourea catalysts derived from cinchona alkaloids. The reaction furnished the desired bicyclic products 43 in good yields and excellent stereoselectivities (Scheme 10.14). 

The hybrid thiourea-cinchona alkaloid catalyst 14 proved to be effective in a stereoselective Michael addition reaction between a,p-unsaturated y-butyrolactam 11 and chalcone 12 (Scheme 3.22). The following mechanistic study addressed the issue of the origin of sfereoselecfion. 

A double-Michael addition of benzofuran-2-ones to divinyl ketones (RCH=CH)2CO, catalysed by various cinchona alkaloid-derived thioureas, has been shown to form spiro-cyclic benzofuran-2-ones (291) with <92% ee and <10 1 dr. DFT calculations were used to shed light on the origin of the stereoselectivity. ... 

Michael addition of benzofiiran-2(3//)-ones (370) to l,l-bis(phenylsulfonyl)ethylene, catalysed by the Cinchona alkaloid-derived thiourea (372), has been reported to exhibit good to excellent stereoselectivities (<99% ee). An interesting effect of the substituent position on stereoselectivity was observed and rationalized by a theoretical study. ... 

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