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首页> 外文期刊>Chemistry: A European journal >Iron(III)-catalyzed cyclization of alkynyl aldehyde acetals: Experimental and computational studies
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Iron(III)-catalyzed cyclization of alkynyl aldehyde acetals: Experimental and computational studies

机译：铁（III）催化炔醛缩醛的环化：实验和计算研究

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摘要

FeCl_3·6H_2O-and FeBr_3-catalyzed Prins cyclization/halogenation of alkynyl aldehyde acetals has been realized with acetyl chloride or bromide as halogen source in dichloromethane to afford 2-(1-halobenzylidene or alkylidene)-substituted five-membered carbo-and heterocycles, and thus provides an alternative route for vinylic C-Cl and C-Br bond formation. Fiveto eight-membered cyclic enones were efficiently synthesized by FeCl_3·6H_2O-catalyzed intramolecular cyclization of alkynyl aldehyde acetals in acetone under mild conditions. An oxocarbonium species generated in situ is proposed to initiate the reaction, and the target products are formed via vinylogous carbenium cation and oxete intermediates according to DFT calculations. Intermolecular reactions of alkynes and aldehyde acetals were also investigated with 20-40 mol% FeCl_3·6H _2O catalyst, and produced α,β-unsaturated enones and chlorinated indene derivatives. The present protocol has applications in the synthesis of carbo-, oxa-and azacycles.
机译：FeCl_3·6H_2O和FeBr_3催化的炔基乙醛缩醛的环化/卤代反应，以乙酰氯或溴为卤素源，在二氯甲烷中提供2-（1-卤代亚苄基或亚烷基）取代的五元碳环和杂环，从而为乙烯基C-Cl和C-Br键的形成提供了另一种途径。通过FeCl_3·6H_2O催化丙酮中炔醛缩醛的分子内环化反应，有效合成了五至八元环烯酮。提出了一种原位产生的氧碳鎓类物质来引发反应，并根据DFT计算，通过乙烯基碳正离子和氧杂环丁烷中间体形成目标产物。还用20-40 mol％FeCl_3·6H _2O催化剂研究了炔烃和乙缩醛的分子间反应，生成了α，β-不饱和烯酮和氯化茚衍生物。本协议在碳，氧杂和氮杂环的合成中具有应用。

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