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Synlett 2007(10): 1561-1564  
DOI: 10.1055/s-2007-982548
LETTER
© Georg Thieme Verlag Stuttgart · New York

An Efficient Route to Benzene and Phenol Derivatives via Ring-Closing Olefin Metathesis

Kazuhiro Yoshida*, Shingo Horiuchi, Noriyuki Iwadate, Fumihiro Kawagoe, Tsuneo Imamoto*
Department of Chemistry, Faculty of Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
Fax: +81(43)2902791; e-Mail: kyoshida@faculty.chiba-u.jp; e-Mail: imamoto@faculty.chiba-u.jp;
Further Information

Publication History

Received 31 January 2007
Publication Date:
06 June 2007 (online)

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Abstract

Without the formation of inseparable regioisomers, ­various substituted phenol derivatives 2 and benzene derivatives 4 were prepared through RCM-tautomerization and RCM-dehydration protocols. A new synthetic route to precursors 1 and 3 enabled efficient access to these aromatic compounds.

Key words

annulations - metathesis - ring closure - ruthenium - ­tautomerism

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The yield ranges were >99-62% (8 to 7), 76-61% (7 to 3), 85-32% (3 to 1). For the preparation of 3b, the reaction of (E)-4-[2-(triisopropylsiloxy)ethyl]-3,6-heptadien-2-one which was easily prepared from 7b, with C2H3MgCl/CeCl3 was performed.

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Typical Experimental Procedure for RCM-Dehydration - Synthesis of 4-Acetoxymethyl-2-methylbiphenyl ( 4e)
To a solution of 1,4,7-trien-3-ol 3e (43.0 mg, 0.150 mmol) in CH2Cl2 (15 mL) was added 7.5 mol% of catalyst 10 (9.3 mg, 0.011 mmol) in one portion under nitrogen. After stirring for 2 h at 40 °C, the reaction mixture was treated with silica gel(excess) and stirred for 1 h at r.t. The mixture was passed through Celite® and the filtrate was concentrated under reduced pressure. Purification by PTLC on silica gel (hexane-EtOAc, 5:1) gave 4e (31.5 mg, 0.131 mmol, 87%). 1H NMR (CDCl3): δ = 2.12 (s, 3 H), 2.29 (s, 3 H), 5.12 (s, 2 H), 7.22-7.36 (m, 6 H), 7.41 (t, J = 7.7 Hz, 2 H). 13C NMR (CDCl3): δ = 20.42, 21.06, 66.19, 125.74, 126.91, 128.10, 129.09, 130.05, 130.30, 134.77, 135.72, 141.42, 141.98, 170.95. HRMS-FAB: m/z calcd for C16H16O2 [M+]: 240.1150; found: 240.1152.

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Typical Experimental Procedure for RCM-Tautomerization - Synthesis of 2-Acetoxymethyl-6-methyl-5-phenylphenol ( 2e)
A solution of 1,4,7-trien-3-one 1e (42.6 mg, 0.150 mmol) in CH2Cl2 (15 mL) was treated with 7.5 mol% of catalyst 10 (9.3 mg, 0.011 mmol) in one portion under nitrogen and stirred for 2 h at 80 °C. The mixture was concentrated under reduced pressure and purified by PTLC on silica gel (hexane-EtOAc, 4:1) to give 2e (36.7 mg, 0.143 mmol, 95%). 1H NMR (CDCl3): δ = 2.13 (s, 3 H), 2.17 (s, 3 H), 5.16 (s, 2 H), 6.82 (d, J = 7.9 Hz, 1 H), 7.15 (d, J = 7.9 Hz, 1 H), 7.27-7.30 (m, 2 H), 7.33 (tt, J = 7.4, 1.2 Hz, 1 H), 7.40 (t, J = 7.7 Hz, 2 H), 8.01 (s, 1 H). 13C NMR (CDCl3): δ = 13.62, 20.95, 63.85, 119.89, 121.78, 124.55, 126.92, 128.03, 128.96, 129.13, 141.53, 144.98, 154.01, 173.97. HRMS-FAB: m/z calcd for C16H16O3 [M+]: 256.1099; found: 256.1095.