Preparation of 4,5-Dialkyl-3-Acyl-Pyrrole-2-Carboxylic Acid Derivatives by Fischer-Fink Type Synthesis and Subsequent Acylation

摘要

#$%^&*AU2011265547A120120202.pdf#####ABSTRACT The present invention relates to an improved synthesis of pyrrole capping group precursors of formula I-a: comprising: combining an aqueous solution of the compound of formula IV-a: wherein R3 is Cl-1 2 aliphatic, C3 -1 2 alkyl-cycloaliphatic, C3 -12 alkyl-aryl, C3- 1 2 alkyl-heteroaryl, or C3- 1 2 alkyl-cycloaliphatic; with a compound of formula V-a, wherein R1 and R2 are each independently Ci-6 aliphatic; in the presence of zinc, water, and optionally an additional suitable solvent to form a compound of formula VI.