Niobium Pentachloride Promoted Conversion of Carboxylic Acids to Carboxamides­: Synthesis of the 4-Aryl-1,2,3,4-tetrahydroisoquinoline Alkaloid­ Structures

Abstract

A practical method for the conversion of carboxylic acids to the corresponding carboxamides mediated by niobium pentachloride under mild conditions is described. The synthesis of the 4-aryl-1,2,3,4-tetrahydroisoquinoline alkaloid structures was accomplished via benzylic lithiation of N-methyl-3,4-dimethoxy-2-(4′-methoxybenzyl)benzamide.

Key words

carboxamides - niobium pentachloride - carboxylic acids - alkaloid - tetrahydroisoquinoline

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Niobium pentachloride with purity >99% was a gift kindly provided by the Brazilian Company of Metallurgy and Mines (CBMM) Araxá city Minas Gerais state Brazil.