(E) and (Z)-α-hydroxy and α-methoxyimino-4-nitro-1H-imidazole-1-acetic acids and esters. Spectral properties,conformations and photoisomerization of the new compounds

Detailed experimental procedures are given for the preparation of the stereoisomeric (E)- and (Z)-methyl-α-hydroxy and α-methoxyimino-4-nitro-1H-imidazole-1-acetates and of the related acids. (Z)-Isomers have been prepared by synthesis. (E)-Isomers have been obtained only by photoisomerization. Decarboxylation of the acids left the corresponding aldehydes which are ideal compounds for structural studies and configurational assignments.