Tautomerism-Dependent Ring Construction of N-Heterocyclic Compounds from the Reactions of 1-Alkynyl Fischer Carbene Complexes and Substituted Pyrazolinones

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• 作者：Zhaoyan Zheng ; Zhengkun Yu ; Ning Luo ; Xiuwen Han
• 刊名：Journal of Organic Chemistry
• 出版年：2006
• 出版时间：December 22, 2006
• 年：2006
• 卷：71
• 期：26
• 页码：9695 - 9700
• 全文大小：109K
• 年卷期：v.71,no.26(December 22, 2006)
• ISSN：1520-6904

文摘

Four types of N-heterocyclic ring systems were successfully constructed from the reactions of 1-alkynylFischer carbene complexes (OC)₅M=C(OEt)CCPh (1) (M = Cr, W) and substituted pyrazolinones(2). Reactions of 1 with 3-methyl-2-pyrazolin-5-one (2a), 3-n-propyl-2-pyrazolin-5-one (2b), 3,4-dimethyl-2-pyrazolin-5-one (2c), 3,4-trimethylene-2-pyrazolin-5-one (2d), or 3,4-tetramethylene-2-pyrazolin-5-one (2e) generated three kinds of Fischer aminocarbene complexes (3-5), and reactions of 1 with phenyl-substituted pyrazolinones, i.e., 3-phenyl-2-pyrazolin-5-one (2f) and its tautomer 3-phenyl-3-pyrazolin-5-one (2g), gave Fischer alkoxycarbene complexes (6) as the major products and aminocarbene complexesof types 3-5 as the minor products. Multiple tautomerism of pyrazolinones is attributed to the versatileformation of N-heterocyclic Fischer carbene complexes. Oxidative demetalation of complexes 3-6 withpyridine N-oxide or m-chloroperoxybenzoic acid efficiently afforded organic carbonyl products, and thus,strongly fluorescent syn-mixed-bimanes were prepared. The present findings constitute an alternativenew method to synthesize mixed bimanes and other novel N-heterocyclic compounds.