Iron(III)-catalyzed cyclization of alkynyl aldehyde acetals: experimental and computational studies.
Iron(III)-catalyzed cyclization of alkynyl aldehyde acetals: experimental and computational studies.
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DOI：
10.1002/chem.201000686
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发表时间：
2010-08
期刊：
影响因子：
--
通讯作者：
Tongyu Xu;Qin Yang;Dongpo Li;Jinhua Dong;Zhengkun Yu;Yuxue Li
中科院分区：
文献类型：
--
作者：
Tongyu Xu;Qin Yang;Dongpo Li;Jinhua Dong;Zhengkun Yu;Yuxue Li
FeCl(3)6 H(2)O- 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. Five- to eight-membered cyclic enones were efficiently synthesized by FeCl(3)6.H(2)O-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)6.H(2)O catalyst, and produced alpha,beta-unsaturated enones and chlorinated indene derivatives. The present protocol has applications in the synthesis of carbo-, oxa- and azacycles.
