1989 年 37 巻 9 号 p. 2361-2368
A method for synthesizing methyl 2, 3-dihydro-2-benzofurancarboxylates from o-allylphenols is described. The reaction of 6-allyl-2, 3-dichlorophenol (3) with benzenesulfenyl chloride (PhSCl) in acetonitrile gave a mixture of PhSCl-adducts, which was heated in aqueous acetonitrile then with sodium bicarbonate to obtain 6, 7-dichloro-2-(phenylthiomethyl)-2, 3-dihydrobenzofuran (6). α-Dichlorination of the phenylthiomethyl group of 6 and subsequent methanolysis gave the methyl ester 5 in high yield. The generality of this synthetic method was examined by the conversion of o-allylphenols 11 having various substituents on the benzene ring into the corresponding methyl esters 23. Cyclizations of 11 to the sulfides 12 could be achieved similarly to hte case of 3. However, in the subsequent conversions of 12 to 23, selective α-dichlorination followed by methanolysis could be achieved only with 12 substituted with an electron-withdrawing group such as a chloro or nitro group.
