Palladium-catalysed carbomethoxyvinylation and thienylation of 5-iodo(bromo)-2,4-dimethoxypyrimidine in water
作者:Ivan Basnak、Satoshi Takatori、Richard T Walker
DOI:10.1016/s0040-4039(97)01015-0
日期:1997.7
(E)-5-(2-Carbomethoxyvinyl)-2,4-dimethoxypyrimidine (2) was prepared in high yield (90%) at room temperature from 5-iodo-2,4-dimethoxypyrimidine (la) via the heterogenous Heck-reaction with methyl acrylate in aqueous solution containing n-Bu4NHSO4 and potassium carbonate. Under the same conditions, using thiophene and heating the mixture under reflux, 5-(2-thienyl)-2,4-dimethoxypyrimidine (3) was obtained in 50% yield starting from la, or in 37% yield starting from 5-bromo-2,4-dimethoxypyrimidine (Ib). Surprisingly, the use of la and thiophene at 150 degrees C in a pressure reactor (50 psi) resulted in a 23% yield of 6-(2-thienyl)-2,4-dimethoxypyrimidine (4) only. (C) 1997 Elsevier Science Ltd.
(E)-5-(乙 carbomethylvinyl)-2,4-双甲氧ypyrimidine(la)在 90% 的高产率下,室温下经过异相 Heck 反应,用甲基 acrylic 酸和 n-Bu4NHSO4、碳酸钾水溶液,制得 2,4-双甲氧ypyrimidine(3)的产物(2)。同样的条件下,用 thiophene 加热混合物回流,由 la 出发,获得了 5-(2- thiophenyl)-2,4-双甲氧ypyrimidine(3),产率为 50%。令人惊讶的是,将 la 和 thiophene 在 150℃,压力反应器(50 psi)下反应,只获得了 6-(2- thiophenyl)-2,4-双甲氧ypyrimidine(4)的 23% 产率。(C)1997 Elsevier Science Ltd。