Synlett 2005(10): 1579-1580  
DOI: 10.1055/s-2005-869860
LETTER
© Georg Thieme Verlag Stuttgart · New York

Selective Reduction of the Exocyclic Double Bond of Isoxazolones and Pyrazolones by Hantzsch 1,4-Dihydropyridine

Zhengang Liu, Bing Han, Qiang Liu, Wei Zhang, Li Yang, Zhong-Li Liu, Wei Yu*
National Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou, Gansu 730000, P. R. China
Fax: +86(931)8625657; e-Mail: yuwei@lzu.edu.cn;
Further Information

Publication History

Received 29 March 2005
Publication Date:
07 June 2005 (online)

Abstract

Hantzsch 1,4-dihydropyridine (HEH) was used to realize the selective reduction of the exocyclic double bond of 4-arylmethylene- and 4-alkylidene-4H-isoxazol-5-ones and 4-arylmethylene-4H-pyrazol-5-ones.

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3-Phenyl-4-(4-nitrophenylmethyl)-2H-isoxazol-5-one (2h): colorless needles; mp 169-171 °C. 1H NMR (300 MHz, DMSO-d 6): δ = 3.42 (1 H, br), 3.82 (2 H, s), 7.43 (2 H, d, J = 8.2 Hz), 7.53 (5 H, s), 8.12 (2 H, d, J = 8.2 Hz). 13C NMR (75.43 MHz, DMSO-d6): δ = 27.4, 94.7, 123.7 × 2 C, 127.5 × 2 C, 127.4, 129.1 × 2 C, 129.3 × 2 C, 131.2, 146.1, 147.8, 162.0, 172.4. MS (EI): m/z (%) = 296 (2) [M+], 136 (100), 77 (5). ESI-HRMS: m/z calcd for C16H12N2O4 + H+: 297.0870; found: 297.0870.