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Synthesis 2007(19): 3032-3036  
DOI: 10.1055/s-2007-983889
PAPER
© Georg Thieme Verlag Stuttgart · New York

A Facile Synthesis of Isochromenes Based on Reactions of 2-Lithio-β-methoxystyrenes with Carbonyl Compounds

Kazuhiro Kobayashi*, Toshiyuki Nagaoka, Shuhei Fukamachi, Yuu Shirai, Osamu Morikawa, Hisatoshi Konishi
Department of Materials Science, Faculty of Engineering, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan
Fax: +81(857)315263; e-Mail: kkoba@chem.tottori-u.ac.jp;
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Publication History

Received 10 May 2007
Publication Date:
11 September 2007 (online)

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Abstract

The reactions of α-substituted 2-lithio-β-methoxystyrenes, generated in situ by bromine-lithium exchange between α-substituted 2-bromo-β-methoxystyrenes and butyllithium in diethyl ether at 0 °C, with carbonyl compounds afforded α-substituted 2-(β-methoxyvinyl)benzyl alcohols, which were treated with a catalytic amount of concentrated hydriodic acid to give 4-substituted iso­chromenes (1H-2-benzopyrans) in reasonable yields.

Key words

heterocycles - ring closure - hydriodic acid - iso­chrom­enes - benzyl alcohols