A Concise Synthesis of Asymmetrically 4,5-Disubstituted 9,9-Dimethyl-9H-xanthenes

Ryosuke Matsubara; Miki Koide; Yong-Soon Shin; Toshiyuki Shimada; Masahiko Hayashi

doi:10.1055/s-0034-1379368

Synthesis, Table of Contents

Synthesis 2015; 47(02): 187-192
DOI: 10.1055/s-0034-1379368

paper

A Concise Synthesis of Asymmetrically 4,5-Disubstituted 9,9-Dimethyl-9H-xanthenes

Ryosuke Matsubara*

Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan Fax: +81(78)8035799 Email: matsubara.ryosuke@people.kobe-u.ac.jp

,

Miki Koide

Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan Fax: +81(78)8035799 Email: matsubara.ryosuke@people.kobe-u.ac.jp

,

Yong-Soon Shin

Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan Fax: +81(78)8035799 Email: matsubara.ryosuke@people.kobe-u.ac.jp

,

Toshiyuki Shimada

Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan Fax: +81(78)8035799 Email: matsubara.ryosuke@people.kobe-u.ac.jp

,

Masahiko Hayashi

Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan Fax: +81(78)8035799 Email: matsubara.ryosuke@people.kobe-u.ac.jp

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Abstract

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Abstract

A concise synthesis of asymmetrically 4,5-disubstituted 9,9-dimethyl-9H-xanthenes was developed. The monolithiation of 4,5-dibromo-9H-xanthene, subsequent zincation, and the Negishi coupling with diverse electrophiles afforded the corresponding 4-aryl- or 4-vinyl-9H-xanthenes in good yields and with high selectivity. The second substitution reactions were performed under mild reaction conditions, thus providing a convenient synthetic route to functionalized molecules based on the 9H-xanthene skeleton.

Key words

xanthenes - metalation - cross-coupling - palladium - zinc

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References

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