Phosphoric Acid-Promoted Synthesis of 4-Acylpyrrole-2-carboxylic Esters and Dipyrryl Ketones from Mixed Anhydrides
作者:Cory S. Beshara、Alison Thompson
DOI:10.1021/jo051906w
日期:2005.12.1
An efficient synthesis of 4-acylpyrrole-2-carboxylic esters utilizing a phosphoric acid-catalyzed mixedanhydride system is described. The new route also enables the preparation of dipyrryl ketones and N-confused dipyrryl ketones.
The condensation of asymmetric β-diketones with α-oximinoacetoacetate esters affords pyrroles regioselectively. The mechanism of the regioselectivity is studied using 13C-NMR spectroscopy. Pyrrole having a neopentyl group at the 4-position is synthesized by the method, and further converted to a steric hindered porphyrin in good yield.