Steric and electronic substituent effects in hydrolysis and aminolysis of 4-alkyl-4-methyl-2-aryl-4,5-dihydro-1,3-oxazol-5-ones
作者:Miloš Sedlák、Roman Keder、Pavel Skála、Jiří Hanusek
DOI:10.1002/poc.928
日期:2005.8
derivatives undergo nucleophilic attack by water at the carbonyl carbon atom at the 5-position of the 1,3-oxazol-5-one ring to the extents of ca 70% and 60%, respectively. Another reaction path consists in nucleophilic attack by water at the 2-position of the 1,3-oxazol-5-one ring. The reaction kinetics of aminolyses of substituted 4-isopropyl-4-methyl-2-phenyl-1,3-oxazol-5(4H)-ones (1a, 1b, 1f) giving
酸催化的取代的4-烷基-4-甲基-2-甲基-2-芳基-4,5-二氢-1,3-恶唑-5-酮水解为相应的2-烷基-2-苯甲酰基氨基丙酸的动力学和机理被研究了。在1,3-恶唑-5-环的4位上的酸催化水解与烷基取代的速率常数的塔夫脱相关性是非线性的。在哈米特(Hammett)相关性中,ρ的值随着烷基取代基的空间需求的增加而降低。对于4-异丙基和叔丁基衍生物,ρ分别为-0.63和-0.32。质子化的4-异丙基和叔丁基衍生物受到水在1,3-恶唑-5-酮环的5位羰基碳原子上的亲核攻击,其程度分别约为70%和60%。另一反应途径是在1,3-恶唑-5-酮环的2-位被水进行亲核攻击。取代的4-异丙基-4-甲基-2-甲基-2-苯基-1,3-恶唑-5(4 H)-ones(1a,1b,1f)的氨解反应动力学,得到取代的N- 1,2-二甲基-在丙胺水溶液中研究了1-[(丙基氨基)羰基]-丙基}苯甲酰胺(3a,3b,