Methanol → 5-(2,3-Dihydro-6-methyl-4-oxo-5-phenyl-1,3-oxazin-3-yl)-5-methyl-2,4-hexanedione

Participants

Reaction Conditions

Reaction Steps

A suspension of magnesium turnings (100 mg) in methanol was stirred whilst a solution of t-butyl [4-(2,3-dihydro-6-methyl-4-oxo-5-phenyl-1,3-oxazin-3-yl)-4-methyl-3-oxo-pentanoate (1.40 g) in methanol was added. The mixture was heated at 60° C. for 1 hour, cooled and evaporated. Toluene was added and the mixture re-evaporated. The residue was redissolved in toluene and a solution of acetyl chloride (300 mg) added. The mixture was stirred at 20° C. for 1 day, then hydrochloric acid (2M) added and the stirring continued for another 1 hour. The organic phase was washed with hydrochloric acid (2M) then with water and dried (magnesium sulphate) 4-Toluene-sulphonic acid (50 mg) was added and the mixture stirred at 80° C. for 1 hour, cooled and washed in turn with saturated sodium bicarbonate solution and water, dried (magnesium sulphate) and evaporated to give 5-(2,3-dihydro-6-methyl-4-oxo-5-phenyl-1,3-oxazin-3-yl)-5-methyl-2,4-hexanedione (Compound 193, 0.15 g) as a brown gum, NMR 1.56(s,6H), 1.91(s,3H), 2.15(s,3H), 3.66 and 3.70(s,1H), 5.25(t,2H), 7.20-7.44(m,5H).

Provenance & Evidence