Synlett 2005(19): 2990-2992  
DOI: 10.1055/s-2005-918955
LETTER
© Georg Thieme Verlag Stuttgart · New York

Triphenylphosphine-Catalyzed Reaction of Aldehydes and Acetylenic Ketones with 1,3-Dicarbonyl Moieties: Synthesis of Multi-Carbonyl Compounds

Song Xue*, Qing-Fa Zhou, Le-Zheng Li, Qing-Xiang Guo
Department of Chemistry, University of Science and Technology of China, Hefei 230026, P. R. of China
Fax: +86(551)3606689; e-Mail: xuesong@ustc.edu.cn;
Further Information

Publication History

Received 7 August 2005
Publication Date:
27 October 2005 (online)

Abstract

A mild and efficient domino process of aldehydes, ­acetylenic ketones and 1,3-dicarbonyl moieties catalyzed by tri­phenylphosphine is reported. The method supplies a facile way to synthesize multi-carbonyl compounds in moderate to good yields. A plausible mechanism is proposed for this domino reaction.

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Typical Procedure.
Benzaldehyde (0.3 mmol), 2,4-pentanedione (0.36 mmol) and phenyl acetylenic ketone (0.36 Lmol) were dissolved in 3 mL CH2Cl2. The mixture was cooled to 0 °C, and 20 mol% PPh3 was added. The resulting mixture was warmed to r.t. and stirred for 6 h. After concentrated under reduced pressure the residue was purified by flash chromatography on silica gel (8:1 PE-EtOAc) to afford the corresponding pure product.
Compound 4a: mp 126-128 °C (lit.14 mp 126-127 °C). 1H NMR (300 MHz, CDCl3): δ = 8.01 (d, J = 7.2 Hz, 4 H), 7.58 (m, 2 H), 7.46 (m, 4 H), 5.38 (t, J = 6.8 Hz, 1 H), 3.97 (t, J = 6.8 Hz, 1 H), 2.51 (t, J = 6.8 Hz, 2 H), 2.27 (s, 6 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 204.4, 196.0, 135.6, 134.0, 129.1, 128.8, 64.8, 53.8, 29.8, 26.9 ppm. IR (neat): ν = 1725, 1696, 1671, 1596, 1580, 1253, 1181 cm-1. HRMS (ESI): m/z calcd for C21H20O4 [M + Na]+: 359.1254; found: 359.1255.
Compound 3a: 1H NMR (300 MHz, CDCl3): δ = 16.66 (s, 1 H), 7.78 (m, 2 H), 7.53 (m, 1 H), 7.45 (m, 2 H), 6.08 (s, 1 H), 6.04 (s, 1 H), 2.01 (s, 6 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 196.4, 191.1 (2 C), 143.5, 136.5, 133.4 133.3, 132.8, 130.7, 111.5, 23.9 (2 C) ppm. IR (neat): ν = 1710, 1657, 1333, 1255, 1198 cm-1. HRMS (EI): m/z calcd for C14H14O3 [M+]: 230.0943; found: 230.0947.