Indium triflate catalyzed reaction of diisopropyl diazomethylphosphonate with imines as a new approach to cis- and trans-aziridine-2-phosphonates
摘要:
A new and efficient synthesis of cis- and trans-aziridine-2-phosphonates by metal-catalyzed aziridination reaction of diisopropyl diazomethylphosphonate and substituted aryl imines is reported. By exploring the influence of different Lewis acids employed as catalysts, imine nitrogen substituents, and the solvent effects we conclude that the best results are obtained when N-d iphenylmethyl- substituted benzylimines are reacted with diisopropyl diazomethylphosphonate in methylene chloride at 0 degrees C in the presence of In(OTt)(3) as catalyst. (c) 2007 Elsevier Ltd. All rights reserved.
A new type of chiral promoter for double asymmetric inductions of aza Diels-Alder and aldol-type reactions of imines is prepared from trialkyl berates (B(OMe)(3) or B(OPh)(3)) and optically pure binaphthol; X-ray analysis of the boron complex demonstrates that it exists as a Bronsted acid-assisted chiral Lewis acid(BLA). The aldol-type reactions of a number of N-benzhydrylimines derived from aromatic aldehydes with the ketene silyl acetal derived from tert-butyl acetate mediated by the chiral BLA afford beta-amino acid esters with high enantioselectivity. The solution conformations of the BLA.imine complexes have been studied using H-1 NMR analysis and difference NOE measurements. The absolute configurations of the adducts can be understood in terms of a rational model involving an intramolecular hydrogen binding interaction via a Bronsted acid.