Sulfuric Acid → 3-Methyl-5-(1-methyl-2(S)-pyrrolidinyl)isoxazole

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Reaction Conditions

Reaction Steps

To the solution of the product from step 25c above was added 12 mL of conc H2SO4, and the mixture was warmed to 70° C. and stirred for 2 hr. The solution was cooled in an ice-water bath, and adjusted to pH 12 by slow addition of 50% aqueous NaOH (40 g). The mixture was extracted twice with ethyl acetate, and the combined extracts were dried over Na2SO4. The solid were removed by filtration, and the filtrate was distilled, first at atmospheric pressure to remove the solvent and, finally, under vacuum to provide the title compound as a nearly colorless liquid (4.74 g, 57%). b.p. 115°-117° C./20 mm Hg. 1H NMR (CDCl3) δ: 1.8-2.1 (m, 3H), 2.32 (s, 3H), 2.21 (m, 1H), 2.29 (s, 3H), 2.36 (m, 1H), 3.17 (m, 1H), 3.53 (t, J=8 Hz, 1H), 6.01 (s, 1H).

Provenance & Evidence