The present invention relates to an improved process for the preparation of (E)-N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide formula (I)
comprising steps of,
(a) condensation of 3,4-dihydroxy-5-nitrobenzaldehyde of formula (II)
with N,N-diethylcyanoacetamide of formula (III)
in the presence of a catalyst and optionally in the presence of phase transfer catalyst in a solvent selected from the group comprising of ethylacetate, acetonitrile, hydrocarbon such as toluene, xylene and like or mixture thereof to give mixture of (E) and (Z)-isomer of N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide of formula (IV).
b) treating an isomeric mixture of (E) and (Z)-isomer of N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide of formula (IV) obtained in step (a) with a halogen in catalytic amounts, in a solvent to give (E)-N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide formula (I).
本发明涉及一种改进的制备(E)-N,N-二乙基-2-
氰基-3-(3,4-二羟基-5-
硝基苯基)
丙烯酰胺式(I)的方法,包括以下步骤:
(a) 在存在催化剂的情况下,将式(II)的
3,4-二羟基-5-硝基苯甲醛与式(III)的N,N-二乙基
氰乙酰胺进行缩合反应,可选地在
乙酸乙酯、
乙腈、
甲苯、二
甲苯等羟基化合物或它们的混合物中进行相转移催化剂的存在下,得到式(IV)的(E)和(Z)异构体的混合物。
(b) 用催化量的卤素在溶剂中处理步骤(a)中得到的(E)和(Z)异构体的混合物,得到(E)-N,N-二乙基-2-
氰基-3-(3,4-二羟基-5-
硝基苯基)
丙烯酰胺式(I)。