Protonation and transformations of α-diazo-β-dicarbonyl compounds in superacids: generation of the strongest carbon-centered cationic electrophiles at the protonation of diazomalonates in Friedel–Crafts reactions
作者:Eugeniy T. Satumov、Jury J. Medvedev、Denis I. Nilov、Maria A. Sandzhieva、Irina A. Boyarskaya、Valerij A. Nikolaev、Aleksander V. Vasilyev
DOI:10.1016/j.tet.2016.06.051
日期:2016.8
Protonation of diazodiketones N2C(COR)2 in Brønsted superacids (TfOH, FSO3H, TfOH–SbF5) gives rise to stable and non-reactive O,O-diprotonated at carbonyl oxygens species N2C(C(OH+)R)2, which were studied by means of 1H and 13C NMR. Diazomalonates N2C(CO2Alk)2, contrary to diazodiketones, react with TfOH or HF, releasing nitrogen and producing triflates of oxymalonates TfOCH(CO2Alk)2 or fluoromalonates
在Brønsted超强酸(TfOH,FSO 3 H,TfOH–SbF 5)中重氮二酮N 2 C(COR)2的质子化作用会生成在羰基氧物种N 2 C(C(OH +)R)2,其通过1 H和13 C NMR研究。与重氮二酮相反,重氮丙二酸酯N 2 C(CO 2 Alk)2与TfOH或HF反应,释放氮并产生三氟甲磺酸酯TfOCH(CO 2 Alk)2或氟丙二酸酯FCH(CO 2 Alk)2, 分别。重氮酮酸酯N 2 C(COR)(CO 2 Alk)仅以相同的方式与TfOH反应,而不与HF反应。重氮丙二酸酯与芳烃ArH(苯,甲苯,二甲苯)在TfOH溶液中的反应产生相应的Friedel-Crafts反应产物ArCH(CO 2 Alk)2。根据进行的DFT计算,由重氮丙二酸二甲酯的质子化衍生而来的可能的中间体三阳离子+ CH(C(OH +)OMe)2应该是迄今为止已知的最强的阳离子碳中心亲电体。