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Synlett 2007(1): 0127-0128  
DOI: 10.1055/s-2006-958407
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Double Suzuki Approach for Synthesis of Substituted Diarylmethylidenefluorenes

C. V. Ramana*, Bonthu K. Kishore Reddy, Challa Nageswara Reddy, Rajesh G. Gonnade, Mukund K. Gurjar
National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
Fax: +91(20)25902629; e-Mail: vr.chepuri@ncl.res.in;
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Publication History

Received 28 September 2006
Publication Date:
20 December 2006 (online)

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Abstract

A convenient synthesis of substituted diarylmethylidenefluorene derivatives, using a double Suzuki reaction, is reported.

Key words

diarylmethylidenefluorene - dibromomethylidenefluorene - Suzuki reaction - arylboronic acids - Pd-mediated coupling

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Selected Experimental Procedure: Under an argon atmosphere, a solution of dibromide 2 (200 mg, 0.6 mmol) in benzene (15 mL) was treated with solid Na2CO3 (154 mg, 1.5 mmol), Pd(PPh3)2Cl2 (40 mg, 0.06 mmol) and boronic acid 3h (145 mg, 0.9 mmol) and the contents were degassed for 5 min. To this, EtOH (0.5 mL) and H2O (0.5 mL) were added and the reaction mixture was heated at 80 °C for 10 h. The reaction mixture was cooled, the catalyst (40 mg, 0.06 mmol) and boronic acid 3h (145 mg, 0.9 mmol) were introduced and the heating at 80 °C was continued for an additional 10 h. In general, the reactions are light-sensitive and covering the reaction vessel with aluminum foil is recommended. The reaction mixture was concentrated under reduced pressure and diluted with EtOAc (30 mL) and washed with H2O. The organic layer was separated, dried (Na2SO4), concentrated and purified by silica gel column chromatography (10% EtOAc-PE). Recrystallization from toluene gave 1h (217 mg, 88%) as yellow colored crystals suitable for single-crystal X-ray diffraction studies. [13]
Spectral Data of Compound 1h: mp 231-233 °C (toluene). IR (CHCl3): 3019, 1682, 1601, 1446, 1403, 1360, 1266, 1215, 1075, 958, 849 cm-1. 1H NMR (200 MHz, CDCl3): δ = 2.65 (s, 6 H), 6.61 (br dt, J = 0.83, 8.0 Hz, 2 H), 6.92 (dt, J = 1.2, 7.4, 8.0 Hz, 2 H), 7.26 (dt, J = 1.0, 7.4 Hz, 2 H), 7.48 (br dt, J = 1.6, 8.1 Hz, 4 H), 7.65-7.74 (m, 2 H), 8.64 (br dt, J = 1.8, 8.1 Hz, 4 H). 13C NMR (50 MHz, CDCl3): δ = 26.6 (q), 119.4 (d), 124.8 (d), 126.6 (d), 128.4 (d), 128.9 (d), 129.9 (d), 135.7 (s), 136.6 (s), 137.8 (s), 140.7 (s), 141.9 (s), 146.9 (s), 197.5 (s). Anal. Calcd for C30H22O2: C, 86.93; H, 5.35. Found: C, 86.97; H, 5.59.

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The crystallographic data for 1h has been deposited with the Cambridge Crystallographic Data Centre with deposition no. CCDC 625077. Copies of the data can be obtained free of charge on application to the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: +44(1223)336033; e-mail: deposit@ccdc.cam.ac.uk].