Metallkomplexe mit biologisch wichtigen Liganden, CXXI [1]. Orthopalladierte Enolate aus N-(Diphenylmethylen)-Schiff-Basen von a-Aminosäureestern als ambivalente 1,3-Dipole in [2+3]-Cycloadditionsreaktionen. Strukturen einer Reihe von Cycloaddukten

Abstract

Enolates of ortho-palladated N-(diphenylmethylene) Schiff bases from glycine esters (R 3 P)Pd[(C 6 H 4 )(C 6 H 5 )C=N-C(R')=CO 2 R] were isolated and have been shown to be ambivalent 1,3-dipoles in [2+3] cycloadditions. Tetracyanoethene, dimethyl acetylene dicarboxylate, dimethyl azodicarboxylate, thiobenzophenone, thione-S, 4-phenyl-l,2,4-triazoline-3,5-dione, diphenyl-ketene and phenylisocyanate are added at the palladium and the enolate (a-C) carbon atoms, whereas methyl propiolate, methyl acrylate, and the methyl esters of maleic and fumaric acid form [2+3] cycloadducts with the «-carbon and the imino carbon atoms of the enolates under mild conditions. The structures of seven cycloadducts were determined by X-ray diffraction analyses.