syn-Selective Asymmetric Mannich Reaction of Sulfonyl Imines with Iminoesters Catalyzed by the N,N,N-Tridentate Bis(imidazolidine)pyridine (PyBidine)-Cu(OTf)2 Complex
Chiral ligand: The [PyBidine–Cu(OTf)2] (Tf=trifluoromethanesulfonate) complexcatalyzed the asymmetricMannichreaction of sulfonylimines and iminoesters to give the products in a high syn‐selective manner. For both 4‐toluene (Ts)‐ and 4‐nitrophenylsulfonyl (Ns)‐imines, the syn‐adducts were obtained in up to 99 % ee (see scheme).
Synthesis of α,β-diamino acid derivatives via asymmetric Mannich reactions of glycine imino esters catalyzed by a chiral phosphoramidite·silver complex
作者:Alberto Cayuelas、Loane Serrano、Carmen Nájera、José M. Sansano
DOI:10.1016/j.tetasy.2014.11.009
日期:2014.12
AgOTf phosphoramidite complexes efficiently catalyze the enantioselective Mannich-type reaction between benzophenone-imine glycine methyl ester and N-tosyl aldimines in the absence of a base. The corresponding syn-adducts, which are the direct precursors of alpha,beta-diamino acids, are obtained with moderate to good syn-diastereoselectivities (up to 9:1) and high enantioselectivities (up to 99% ee). (C) 2014 Elsevier Ltd. All rights reserved.