Synthesis and selected transformations of 1H-imidazole 3-oxides derived from amino acid esters

Abstract

A series of new optically active 1H-imidazole 3-oxides 5 with a substituted acetate group at N(1) as the chiral unit were prepared by the reaction of a-(hydroxyimino) ketones, a-amino acid methyl esters, and formaldehyde. In an analogous reaction, ethyl 2-(hydroxyimino)-3-oxobutyrate and 1,3,5- trialkylhexahydro-1,3,5-triazines gave 3-oxido-1H-imidazole-4-carboxylates 14, which easily rearranged into the 2-oxo derivatives 15. Selected examples of N-oxides 5 could be transformed into the corresponding 2,3-dihydro-1H-imidazole-2-thione derivatives 10 via a 'sulfur-transfer reaction', and the reduction of the histidine derivative 5i with Raney-Ni yielded the optically active 2,3-bis(imidazolyl)propanoate 12.
Furthermore, reaction of the (1H-imidazol-1-yl)acetates with primary amines yielded the corresponding acetamides.