A novel bifunctionalchiral pyridoxal derivative 1 with a bigger catalytic cavity than that of previous pyridoxal catalysts promoted direct asymmetric α-C allylation of NH2-unprotected glycinates with Morita–Baylis–Hillmanacetates. In this way, the chemoselectivity for glycinates was switched from intrinsic N-allylation to α-C allylation to produce chiral glutamic acid esters with excellent stereoselectivity
Asymmetric Synthesis of 2-Alkyl-3-phosphonopropanoic Acids via P−C Bond Formation and Hydrogenation
作者:Pallavi A. Badkar、Nigam P. Rath、Christopher D. Spilling
DOI:10.1021/ol701500s
日期:2007.8.1
Allylic acetates, formed by the acetylation of Baylis Hillman adducts, undergo addition of phosphorus nucleophiles to give stereoselectively the Z-unsaturated esters. TFA cleavage of the tert-butyl ester and asymmetric hydrogenation of the unsaturated acid yields the phosphono alkyl propanoic acid moiety, commonly found in phosphonate- and phosphinate-based enzyme inhibitors.