New tripodal uranyl ion chelators containing gem-bisphosphonic units have been synthesized. All bisphosphonic units present a side chain with 0, 1, or 2 methylene group terminated by -NH2 or -COd(2)H group. These units were respectively coupled with a -CO2H or -NH2 functions of a suitable tri-functional platform. The shape and size of the new designed ligands were selected and validated through computer molecular modelization. (c) 2007 Elsevier Ltd. All rights reserved.
L-aspartic acid bis(trimethylsilyl) ester: a convenient starting material for the acylation of L-aspartic acid.
作者:Ana M. Castano、Antonio M. Echavarren
DOI:10.1016/0040-4020(92)85013-5
日期:1992.1
Reaction of L-aspartic acid with excess of bis(trimethylsilyl)amine under reflux provides optically pure L-aspartic acid bis(trimethylsilyl) ester in quantitative yield. This silyl ester reacts with a variety of acylating reagens in tetrahydrofuran to give N-protected aspartic acids and dipeptides in good yields without racemization.