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Synthesis 2008(6): 859-864  
DOI: 10.1055/s-2008-1032207
PAPER
© Georg Thieme Verlag Stuttgart · New York

Concise Synthesis of Diborylxanthenes

Takeshi Makino, Ryu Yamasaki, Shinichi Saito*
Department of Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
Fax: +81(3)52614631; e-Mail: ssaito@rs.kagu.tus.ac.jp;
Further Information

Publication History

Received 23 October 2007
Publication Date:
28 February 2008 (online)

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Abstract

A simple and efficient synthesis of a series of bidentate diborylxanthene derivatives is described.

Key words

boron - cross-coupling - Lewis acids - ipso-substitution - xanthene

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18

The reaction of lithiated 10 with Β-bromocatecholborane gave 3b in low yield (10%).

24

The 11B NMR chemical shifts of 1c, 2c and 3c were not observed, probably because the signals were too broad.

25

It is not adequate to discuss the Lewis acidity by the values of 11B NMR chemical shifts. See ref. 16.