Guanidine catalysts phospha-Michael reactions

The mechanism and origin of enantioselectivity has been evaluated for a bicyclic guanidine-catalyzed phospha-Michael reaction between diphenyl-phosphine oxide and p-nitrostyrene by DFT calculations (Scheme 32). The catalyst was found to be involved in all three steps of the catalytic cycle proposed. 

Terada expanded the phospha-Michael reaction to include diphenyl-phosphites [128]. A novel binaphthol-derived guanidine catalyst promoted the addition in high yields and enantioselectivities (Scheme 73). Functionalizing the external nitrogen with a diphenylmethine moeity enhanced selectivities for a large scope of nitro-olefm derivatives. 

Scheme 4.75 The catalytic enantioselective phospha-Michael reactions using guanidines as catalysts.

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