benzhydryl (2S,3R,5R)-3-formyl-3-methyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate → Benzhydryl (E)-(2S,3S,5R)-3-methyl-3-[2-(1,2,4-oxadiazol-3-yl)-vinyl]-7-oxo-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylate

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Reaction Steps

1.14 g (3.0 mmol) of benzhydryl (2S,3R,5R)-3-formyl-3-methyl-7-oxo-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylate were dissolved in 15 ml of 1,2-butylene oxide, treated with 1.38 g (3.6 mmol) of (1,2,4-oxadiazol-3-yl)methyl-triphenylphosphonium chloride and refluxed for 10 hours. Subsequently, the mixture was filtered, the filtrate is evaporated and the residual brown oil was chromatographed over silica gel (0.040-0.063 mm particle size) with methylene chloride as the eluent. Yield: 280 mg (21%) of colorless crystals MS: (M+NH4)+ 465.3 IR (KBr): 1792, 1753, 1658, 1492, 1200, 991 cm-1

Provenance & Evidence