Rapid Procedure for N-Phthaloylation of α-Amino Carboxamides, α-Amino Alcohols, α-Amino Esters and Dipeptide Derivatives

Abstract

A rapid, one-pot synthesis and mild procedure for the N-phthaloylation of α-amino carboxamides is described. In acetonitrile, these derivatives react with mono-methylphthalate in the presence of BOP and i-Pr₂NEt to afford the intermediate N ^α-[(o-methoxycarbonyl)benzoyl]amino carboxamides, which undergo rapid cyclization in the presence of aqueous sodium carbonate to afford the corresponding N ^α-phthaloylamino carboxamides in excellent yields. The reaction also works efficiently with α-amino esters, α-amino alcohols and dipeptide esters or amides.

Key words

phthaloyl protection - α-amino carboxamides - mono-methylphthalate - α-amino alcohols - cyclization

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In both cases, the ratio l/d was >99:1.