C[Si](C)(C)[C:3](=[O:16])[C:4]([F:15])([F:14])[CH:5]([C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1)[CH:6]=[CH2:7].[N+](=[CH:21][CH2:22][CH2:23][CH2:24][CH3:25])=[N-].C(N(N=O)C(N[N+]([O-])=O)=N)CCCC.[OH-].[K+]>C(OCC)C>[F:14][C:4]([F:15])([C:3](=[O:16])[CH2:21][CH2:22][CH2:23][CH2:24][CH3:25])[CH:5]([C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1)[CH:6]=[CH2:7]
Trimethyl-(2,2-difluoro-3-phenyl-4-pentenoyl)silane (400 mg, 1.5 mmol) was dissolved in diethyl ether (10 ml). The resulting solution was cooled to 0° C. and etheral 1-diazopentane [prepared from 1-pentyl-3-nitro-1-nitrosoguanidine (0.6 g) added slowly to a two-phase mixture of aqueous KOH (0.67 g in 2 ml of water) and ethyl ether (10 ml)] was added dropwise. The mixture was then stirred at room temperature for 12 hours, refluxed for 0.5 hours and allowed to cool to room temperature. Excess diazopentane was destroyed and the enol ether hydrolyzed by the addition of excess aqueous acetic acid. The mixture was concentrated in vacuo to give 731 mg of crude product. This material was purified by flash chromatography using 1:4 chloroform:hexane as eluant. Pure fractions were combined and concentrated to provide 99 mg (24% yield) of title product as a viscous yellow oil. 1H-NMR(CDCl3)delta(ppm): 7.32 (m, 5H), 6.16 (ddd, 10 12 and 20 Hz, 1H), 5.32 (d, 12 Hz, 1H), 5.24 (d, 20 Hz, 1H), 4.06 (dt, 10 and 16 Hz, 1H), 2.50 (dt, 7 and 17 Hz, 1H), 2.28 (dt, 5 and 17 Hz, 1H), 1.45 (m, 2H), 1.16 (m, 4H), 0.84 (t, 6 Hz, 3H). 13C-NMR(CDCl3)delta(ppm): 134.87, 132.03, 129.51, 128.70, 127.93, 120,62, 120.40, 117.25, 114.00, 53.27, 52.98, 52.67, 37.86, 30.85, 22.24, 21.93, 13.79. IR (CDCl3) cm-1 : 2925, 1739. Mass spectrum m/e (relative intensity): M+ 276.1 (1).
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