LEWIS ACID-PROMOTED HETERO-DIELS-ALDER REACTION OF ALPHA,BETA-UNSATURATED THIOKETONES

被引：26

作者：

MOTOKI, S ^{[1
]}

SAITO, T ^{[1
]}

KARAKASA, T ^{[1
]}

MATSUSHITA, T ^{[1
]}

FURUNO, E ^{[1
]}

机构：

[1] NIPPON DENT UNIV TOKYO,CHIYODA KU,TOKYO 102,JAPAN

来源：

JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1 | 1992年 / 21期

关键词：

D O I：

10.1039/p19920002943

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

Alpha,beta-Unsaturated thioketones 1 were regenerated from their precursors, the dithiine-type dimers 3, and readily underwent the Lewis acid-promoted hetero Diels-Alder reactions with a variety of carbonyl-activated dienophiles such as methyl acrylate 4, methyl vinyl ketone 6, acrolein 7, N,N-dimethylacrylamide 8, methyl methacrylate 9, dimethyl fumarate 10, methyl crotonate 11 and N-p-tolylmaleimide 12, to give [4 + 2]cycloadducts 5 and 13-19, respectively. Among the Lewis acids investigated, AlCl3 and EtAlC12, when used in diethyl ether and dichloromethane, respectively, were found to remarkably accelerate the reaction even at lower temperatures (25-35-degrees-C); the reaction is very slow in the absence of the catalyst. A moderate enhancement of the stereoselectivity (endo/exo) was observed compared with that of the thermal reactions at 80-degrees-C in benzene. The structure determination of the cycloadducts by H-1 NMR spectroscopic studies are described and the configurations and relative conformations are also discussed.

引用

页码：2943 / 2948

页数：6

共 27 条

[11] ALUMINUM CHLORIDE CATALYZED DIENE CONDENSATION .6. PARTIAL RATE FACTORS OF 2-PHENYLBUTADIENES, 2-CHLOROBUTADIENES 2-TRIFLUOROMETHYLBUTADIENES, AND 2-CYANOBUTADIENES IN REACTIONS WITH METHYL ACRYLATE - DIFFERENTIAL HAMMETT CORRELATION [J].