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Synlett 2011(15): 2177-2180  
DOI: 10.1055/s-0030-1261199
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of meso-Substituted Tetraarylalkynylporphyrins via Rhenium-Catalyzed Formation of Naphthalene Units

Ali Samarata, Yoichiro Kuninobu*b, Kazuhiko Takai*b
a University of Carthage, Faculty of Sciences of Bizerte, Jarzouna 7021, Bizerte, Tunisia
b Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama 700-8530, Japan
Fax: +81(86)2518094; e-Mail: kuninobu@cc.okayama-u.ac.jp; e-Mail: ktakai@cc.okayama-u.ac.jp;
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Publication History

Received 11 July 2011
Publication Date:
30 August 2011 (online)

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Abstract

Rhenium-catalyzed synthesis of naphthalene-substituted aryl bromides or iodides via C-H bond activation, and its use for palladium-catalyzed cross-coupling reactions with tetraethynylporphyrin are described. A series of novel meso-substituted tetraalkynylporphyrins with naphthalene moieties were obtained.

Key words

rhenium catalyst - C-H bond activation - naphthalene derivative - Sonogashira coupling - meso-substituted tetraalkynyl­porphyrin

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General Procedure for the Synthesis of Naphthalene Derivatives 6 by One-Pot Reaction A mixture of N-(diphenylmethylene)aniline (1, 129 mg, 0.500 mmol), 4-bromobenzaldehyde (2a, 1.00 mmol) or 4-iodobenzaldehyde (2b, 1.00 mmol), olefin (4, 0.600 mmol), 4 Å MS (200 mg), [ReBr(CO)3(thf)]2 (10.6 mg, 0.0125 mmol), and toluene (1.0 mL) was stirred at 115 ˚C for 48 h. Then, AcOH (3.0 mL) and H2SO4 (1.0 mL) were added, and the mixture was stirred at r.t. for 2 h. The crude product was extracted with hexane and purified by column chromatography on silica gel or recrystallized from EtOH to give naphthalene derivative 6.

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Typical Procedure for the Synthesis of meso -Substituted Tetraarylalkynylporphyrin 9a Porphyrins 7 ¹¹ and 8 ¹²a were prepared according to the reported methods. To a degassed solution of zinc(II) 5,10,15,20-tetraethynylporphyrin (8, 10 mg, 0.021 mmol), 1-(4-iodophenyl)-4-phenylnaphthalene-2,3-dicarboxylic acid diethyl ester (6d, 75.4 mg, 0.137 mmol), and AsPh3 (12 mg, 0.038 mmol) in a mixture of anhyd THF (10 mL) and Et3N (5.0 mL) was added Pd2(dba)3 (2.0 mg, 0.0020 mmol). The reaction mixture was stirred at 50 ˚C for 4 h under an argon atmosphere. The solvent was evaporated under reduced pressure, and the crude product was purified by column chromatography on silica gel using CHCl3 as an eluent to give a dark green solid 9a (41.7 mg, 92%). ¹H NMR (400 MHz, CDCl3): δ = 0.96 (t, J = 7.2 Hz, 12 H), 1.17 (t, J = 7.2 Hz, 12 H), 4.03 (q, J = 7.2 Hz, 8 H), 4.19 (q, J = 7.2 Hz, 8 H), 7.43-7.55 (m, 28 H), 7.68-7.71 (m, 12 H), 7.85 (d, J = 8.4 Hz, 4 H), 8.27 (d, J = 8.0 Hz, 8 H), 9.48 (s, 8 H). ¹³C NMR (100 MHz, CDCl3): δ = 13.6, 13.9, 61.4, 61.6, 66.7, 92.8, 96.9, 102.7, 123.7, 127.1, 127.5, 127.8, 127.9, 128.1, 129.0, 129.2, 130.2, 130.7, 131.2, 131.5, 132.6, 132.8, 137.7, 138.3, 138.4, 139.3, 151.3, 168.3, 168.4. IR (Nujol): 480, 771, 941, 1132, 1166, 1222, 1300, 1676, 1685, 1716, 1734, 2213, 2924 cm-¹.