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本文报道了一种新的选择性制备单乙酰基保护1,1-环丙基二甲醇(2)的方法。2与2-溴-1,1-二甲氧基乙烷经酸催化进行缩醛交换反应得6-溴甲基-5,7-二氧杂螺[2.5]辛烷(4),4先在叔丁醇钾作用下脱HBr得环烯缩酮,再经氢溴酸水溶液水解得1-(溴甲基)环丙基甲基乙酸酯(5)。该法避免了苯甲酰基保护单羟基时选择性差、原料损失严重、收率低等问题。5再经氰基取代、水解得1-(羟甲基)环丙基乙腈(7),7经溴代后与硫脲反应,再经水解、酸化得1-(巯甲基)-环丙基乙酸(1),总收率58%。
In this paper, a new method for the selective preparation of monoacetyl-protected 1,1-cyclopropyldimethanol (2) has been reported. 2 and 2-bromo-1,1-dimethoxyethane were subjected to acetal exchange reaction with acid to obtain 6-bromomethyl-5,7-dioxaspiro [2.5] octane Under the action of potassium tert-butoxide, deprotection of HBr to cyclohexene ketal and hydrolysis of hydrobromic acid to give 1- (bromomethyl) cyclopropylmethyl acetate (5). The method avoids the problems of poor selectivity, serious loss of raw materials and low yield when the benzoyl group protects the monohydroxy group. 5 and then by cyano-substituted, hydrolysis of 1- (hydroxymethyl) cyclopropylacetonitrile (7), 7 after the reaction with thiourea bromide, and then hydrolysis, acidification 1- (mercaptomethyl) - cyclopropane Glycine (1), total yield 58%.