New Models for the Study of the Racemization Mechanism of Carbodiimides. Synthesis and Structure (X-ray Crystallography and <sup>1</sup>H NMR) of Cyclic Carbodiimides
作者:Pedro Molina、Mateo Alajarín、Pilar Sánchez-Andrada、Juan Server Carrió、Martín Martínez-Ripoll、J. Edgar Anderson、María Luisa Jimeno、José Elguero
DOI:10.1021/jo951789c
日期:1996.1.1
22,24-tetraazapentacyclo[23.3.1.1(3,7).1(11,15).1(17,21)]dotriaconta-1(29),3,5,7(32),8,9,11,13,15(31),17,19,21(30),22,23,25,27-hexadecaene) have been determined. The activation barriers for the racemization of carbodiimides 1 (6,7-dihydrodibenzo[d,h][1,3]diazonine), 2, and 3 have been determined. While 1 presents a relatively high barrier (17.4 kcal mol(-)(1)), 2 and 3 have very low activation barriers
碳二亚胺2(5,6,18,19-tetradehydro-5,12,13,18,25,26-hexahydrotetrabenzo [d,h,m,q] [1,3,10,12]的晶体和分子结构四氮杂十八环辛]和3(8,10,22,24-四氮杂五环[23.3.1.1(3,7).1(11,15).1(17,21)] dotriaconta-1(29),3,5,7已确定(32),8,9,11,13,15(31),17,19,21(30),22,23,25,27-十六碳烯)。已经确定了碳二亚胺1(6,7-二氢二苯并[d,h] [1,3]二氮嗪),2和3外消旋化的激活势垒。虽然1呈现相对较高的势垒(17.4 kcal mol(-)(1)),但是2和3具有非常低的激活势垒(5到7 kcal mol(-)(1)之间)。我们初步得出结论,开环和大环碳二亚胺通过氮反转或反式旋转而消旋,而中型环状碳二亚胺通过顺式旋转而消旋。