Cyclopropenone Oximes: Preparation and Reaction with Isocyanates

Article abstract of DOI:10.1246/bcsj.61.4347

2,3-Diphenyl-, 2-methyl-3-phenyl-, and 2-methyl-3-(4-methylphenyl)cyclopropenone oxime hydrochlorides (3) were prepared in good yields from the corresponding cyclopropenones and hydroxylamine hydrochloride in methanol.The salts 3 reacted with alkyl and aryl isocyanates in the presence of triethylamine to afford 1 : 2 addition products 4,6-diazaspiro<2,3>hexenones in moderate yields.In contrast, acetone, acetophenone, and cyclohexanone oximes reacted with twice excess of methyl isocyanates to give linear 1 : 1 addition products and benzophenone oxime yielded only 1 : 1 addition product.