A divergent synthesis of dihydropyridazinones, N-substituted dihydropyrazoles, and O-substituted pyrazoles
作者:Eiichi Masumoto、Hiroshi Maruoka、Fumi Okabe、Sho Nishida、Yuki Yoshimura、Toshihiro Fujioka、Kenji Yamagata
DOI:10.1002/jhet.519
日期:2011.1
Dihydropyridazinones 4a, 4b, N‐substituted dihydropyrazoles 5b, 5c, 5d, and O‐substituted pyrazoles 6a, 6b, 6c, 6d have been synthesized starting from spirocyclopropanepyrazole derivative 2. Treatment of 2 with α‐chloro esters, e.g., methyl chloroacetate, ethyl chloroacetate, isopropyl chloroacetate, and tert‐butyl chloroacetate, in potassium carbonate/sodium iodide system caused ring opening and subsequent
从螺环丙烷吡唑衍生物2开始合成了二氢哒嗪酮4a,4b,N-取代的二氢吡唑5b,5c,5d和O-取代的吡唑6a,6b,6c,6d。在碳酸钾/碘化钠体系中,用α-氯酸酯(例如,氯乙酸甲酯,氯乙酸乙酯,氯乙酸异丙酯和氯乙酸叔丁酯)处理2导致开环和随后的C或N攻击亲核取代得到相应的二氢吡嗪酮4a,4b和N-取代的二氢吡唑5b,5c,5d。在另一方面,在不存在碘化钠,ö取代吡唑图6a,图6b,图6c,图6d为得自2 经由一个ö -attack亲核取代。J.杂环化学.2011。