Preparation of pyrrol and oxazole compounds: formation of C-acyl-α-amino acid esters therefrom
A process for preparation of new or previously known pyrrol derivatives is provided. The process involves reacting a nitroalkane or a nitroalkene with an isocyanoacetate in the presence of a proprophosphatrane "super base" to prepare the pyrrol compounds. Through production of new pyrrol compounds, new pyrrol derivatives such as dipyrromethane and porphyrin may be synthesized. In addition, the high yields of pyrrol compounds produced according to the method of the invention provide for more efficient production of previously known dipyrromethane and porphyrin compounds. The invention further provides a mild, high yield process for de-esterification of esterified pyrrol and dipyrromethane compounds. The invention also provides a synthetic method for the production of high yields of oxazoles through reaction of an aryl halide or acid anhydride with an isocyanoacetate in the presence of a prophosphatrane "super base". The product oxazoles serve as intermediates for subsequent treatment to provide pharmaceutically interesting C-acyl-α-amino acid esters.