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	Lewis acid-controlled reactions of zirconacyclopentadienes with isocyanates and isothiocyanates. One-pot three- or four-component synthesis of multiply substituted iminocyclopentadienes and butadiene-tethered 1,6-bisamides and electrophilic cycli
	Hu, Qiaoshu ; Lu, Jiang ; Wang, Congyang ; Wang, Chao ; Xi, Zhenfeng
	2007
关键词	TRANSITION-METAL COMPLEXES OPPENAUER-TYPE OXIDATION MEDIATED REACTIONS ALLYLIC ALCOHOLS CYCLOPENTADIENE DERIVATIVES TETRAHYDROFURAN DERIVATIVES CYCLOADDITION REACTIONS CATALYZED REACTIONS ORGANIC-SYNTHESIS BOND FORMATION
英文摘要	Multiply substituted zirconacyclopentadienes including bicyclic zirconacyclopentadienes and zirconaindenes reacted with isocyanates and isothiocyanates in the presence of Lewis acids to afford iminocyclopentadienes and conjugated 1,6-bisamides, depending on the nature of Lewis acids, isocyanates, and isothiocyanates used. Only in the presence of BF3 could iminocyclopentadienes be obtained in high isolated yields when zirconacyclopentadienes were treated with isocyanates. On the contrary, BF3 could not mediate the reaction of zirconacyclopentadienes with isothiocyanates. For the reactions of zirconacyclopentadienes with isothiocyanates, EtAlCl2 was found effective to generate iminocyclopentadienes as the products. Interestingly, however, for the reactions of zirconacyclopentadienes with isocyanates, EtAlCl2 was found to work very differently from BF3. Instead of iminocyclopentadienes, conjugated 1,6-bisamides and conjugated monoamides were obtained as products in high isolated yields from the reactions of zirconacyclopentadienes with isocyanates, depending on the substituents of isocyanates. The reaction path and products could be controlled by Lewis acids. As a demonstration of the usefulness of thus obtained unsaturated bisamides, electrophilic cyclization using acids, NBS, and I-2 was carried out. Electrophilic cyclization of multisubstituted conjugated 1,6-bisamide derivatives afforded cyclic iminoethers in excellent yields with perfect selectivity. Only one of the amide groups took part in the electrophilic cyclization. (C) 2007 Elsevier Ltd. All rights reserved.; Chemistry, Organic; SCI(E); CPCI-S(ISTP); 0
语种	英语
DOI标识	10.1016/j.tet.2007.02.015
内容类型	其他
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/250038]
专题	化学与分子工程学院
推荐引用方式 GB/T 7714	Hu, Qiaoshu,Lu, Jiang,Wang, Congyang,et al. Lewis acid-controlled reactions of zirconacyclopentadienes with isocyanates and isothiocyanates. One-pot three- or four-component synthesis of multiply substituted iminocyclopentadienes and butadiene-tethered 1,6-bisamides and electrophilic cycli. 2007-01-01.

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