Tropos Biphenol Derived Chiral Thiophosphoramide Catalysed Highly Diastereo- and Enantioselective Michael Addition of Cyclic Ketones to Nitro Olefins

Chirality transfer from (S)-2-(aminomethyl)pyrrolidine to the tropos biphenyl skeleton has been observed in the preparation of a chirally flexible biphenol-derived novel chiral thiophosphoramide to afford exclusively the thermodynamically favoured diastereomer. This novel secondary amine-thiophosphoramide has proven to be an effective bifunctional organocatalyst for the asymmetric Michael addition of cyclohexanone to both aryl- and alkyl-substituted nitro olefins. The corresponding adducts were obtained with excellent diastereo- (up to >99:1 dr) and enantioselectivities (up to >99% ee).