Sulfuric Acid → Ethyl 5,5-diphenyl-2-isoxazoline-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

The crude cyclopropane derivative, 2,2-diphenylcyclopropanyl carboxylate ethyl ester (generated through the reported one step procedure as a crude product in 107% yield) (21.3 g, 80 mmol) was dissolved in 80.0 mL AcOH at room temperature (18° C.). Into the solution was carefully added 40.0 mL concentrated H2SO4, followed by adding NaNO2 (6.1 g, 88 mmol, 1.1 eq) in several portions so that the reaction temperature did not excess 40° C. After addition, the reactants were stirred at room temperature (about 18° C.) for half an hour. And the reactants were poured into an iced water and extracted with diethyl ether (2×200 mL), the ethereal solutions were combined and washed with sat. NaHCO3 (2×100 mL), then water (100 mL) and brine (50 mL) in sequence. The washed ethereal solution was then dried over Na2SO4. After removing the desiccant, the ethereal solution was concentrated to furnish a thick oily crude product. The 1H NMR of the crude product showed that the reaction was clean and a virtual 100% yield. The thick oily crude product was stirred with 10 mL petrol to give a pale yellow solid 21.7 g, 92% yield (98% over yield in two steps based on diphenyl ketone hydrazine).

Provenance & Evidence