Synthesis and Selected Transformations of 1 H ‐Imidazole 3‐Oxides Derived from Amino Acid Esters

A series of new optically active 1 H ‐imidazole 3‐oxides 5 with a substituted acetate group at N(1) as the chiral unit were prepared by the reaction of α ‐(hydroxyimino) ketones, α ‐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‐1 H ‐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‐1 H ‐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 (1 H ‐imidazol‐1‐yl)acetates with primary amines yielded the corresponding acetamides.