4-甲基-5-乙氧基噁唑合成工艺研究

Study of the Synthetic Process of 4-Methyl-5-ethoxyoxazole

采用N 乙氧草酰丙氨酸乙酯经环合、水解、酸析和脱羧合成维生素B6的重要中间体 4 甲基 5 乙氧基口恶唑。选用三氯氧磷 /三乙胺 /甲苯 /二甲基甲酰胺作为环合脱水剂 ,当n(N 乙氧草酰丙氨酸乙酯 )∶n(三氯氧磷 )∶n(三乙胺 ) =1 0∶(1 0～ 1 2 )∶(3 5～ 4 2 )时 ,80℃下反应 8h ,环合反应收率为 91 7% ;水解、酸析和脱羧三步一锅 ,收率为 88.2 %。每步产品均运用IR。

4-Methyl 5 ethoxyoxazole(Ⅰ),an important intermediate of Vitamin B 6,was synthesized through cycloaddition,hydrolysis,acidification and decarboxylation.Choosing POCl 3/Et 3N/CH 3C 6H 5/(CH 3) 2NCHO as cycloaddition and dehydration agent,when n [CH 3CH(NHCOCO 2Et)CO 2Et]∶ n (POCl 3) ∶ n (Et 3N) = 1 0∶(1 0-1 2) ∶(3 5-4 2),the reaction was carried out for 8 h at 80 ℃ to give 4 methyl 5 ethoxy 2 oxazolecarboxylic acid ethyl ester(Ⅱ) in 91 7% yield.I was successfully prepared from Ⅱ in 88 2% yield through hydrolysis,acidification and decarboxylation in one pot.Analysis of the compounds was done by means of IR and 1HNMR.