反应详情

A solution of the crude intermediate 4-methyl-5-ethyl-tetrahydro-1,4-oxazine-3-one was prepared in a manner similar to that described in Example I by reacting the sodium salt of 2-amino-butan-1-ol (from 240 g of the amino alcohol and 62 grams of sodium) in 2500 ml of tetrahydrofuran with 338 g of ethyl chloroacetate following alcohol and 62 grams of sodium) in 2500 ml evaporation of the reaction solvent, the crude product was taken up in chloroform and washed with water. After drying the organic solution and removal of the solvent, recrystallization of the crude product from isopropyl ether/ethyl acetate yielded 151 grams of 5-ethyl-tetrahydro-1,4-oxazin-3-one, m.p. 70°-73°. Absence of carbonyl absorption bands in the infrared in the lactone region and the presence of a strong band at 6.10μ confirmed lactam rather than lactone cyclisation. Other major IR bands: 3.42, 3.52, 6.7, 6.8, 7.0, 7.2, 7.5, 7.8, 8.0, 8.7, 8.9, 8.98, 9.2, 9.5, 10.1, 10.5, 10.9, 11.8, 12.4 and 13.8μ NMR(CDCl3,δ): 2.95, singlet, NCH3 ; 3.2, multiplet, N-CH(CH2CH3); 1.75, quintet, CH2 (CH3); 0.93 triplet, CH3 (CH2); 3.78 and 3.84, AB pair, CH2O; 4.07 singlet, CH2CO.

1. customin 2500 ml evaporation of the reaction solvent
2. washwashed with water
3. customAfter drying
4. customthe organic solution and removal of the solvent, recrystallization of the crude product from isopropyl ether/ethyl acetate