Synthesis and Reactions of 2-Arylhydrazinotropones. I. Preparation of 2-(2-Arylhydrazino)tropones and the 4-Substituted Derivatives

Article abstract of DOI:10.1246/bcsj.61.2531

A wide variety of 2-(2-arylhydrazino)tropones were prepared by the reactions of 2-tosyloxytropone with arylhydrazines.The dimeric compounds 6,6'-bis(arylhydrazono)-1,1'-bi(2,4-cycloheptadiene)-7,7'-diones, 2-anilinotropones, and 3-(2-arylhydrazino)tropones were isolated as minor products in some cases.Similarly, starting with 2-tosyloxytropones bearing an isopropyl, isopropenyl, (1-acetamidoethyl), and protected acetyl group at the 5-position, 4-substituted 2-(2-arylhydrazino)tropones were obtained as the major products by the abnormal substitution reaction.These 2-(2-arylhydrazino)tropones are expected to effectively serve as precursor for a convenient synthesis of 5-aryl-substituted tropolones via benzidine-type rearrangement. 1H NMR (200 or 500-MHz) parameters for these 4-substituted 2-(2-arylhydrazino)tropones are given for their unambiguous structural assignments.