反应详情

Lithium diisopropylamide (0.91 ml, 1.5M in cyclohexane) was added dropwise under nitrogen to a stirred solution of diethyl 3-fluoro-3(1-trityl-1,2,4-triazol-3-yl)propane phosphonate (0.35 g, prepared as described in Example 27) whilst maintaining the temperature below -60° C. After five hours, the mixture was allowed to warm then stand at room temperature overnight. It was then poured on to saturated ammonium chloride solution and extracted with ethyl acetate. The extracts were dried over magnesium sulphate and evaporated under reduced pressure. The residue was chromatographed on silica, using dichloromethane-ethanol (19:1) as eluant, to give diethyl 2(1-trityl-1,2,4-triazol-3-yl)cyclopropane phosphonate (0.18 g). NMR (CDCl3): δ 1.3(6H,2 xt), 1.4-1.5(3H,m), 2.6-2.7(1H,m), 4.05-4.2(4H,m), 7.1-7.3(15H,m), 7.8(1H,s). M/S: M+ 487. The basic structure was confirmed by 13C, 19F, 31 p, COSY and NOESY experiments but stereochemistry could not be assigned. Theoretical calculations suggested that the trans (1RS,2RS) isomer is likely to be much more stable and thus preferred.

1. temperaturewhilst maintaining the temperature below -60° C
2. temperatureto warm
3. waitthen stand at room temperature overnight
4. extractionextracted with ethyl acetate
5. dry with materialThe extracts were dried over magnesium sulphate
6. customevaporated under reduced pressure
7. customThe residue was chromatographed on silica