Electronic and Steric Effects on the Mechanism of the Inverse Electron Demand Diels−Alder Reaction of 2-Aminopyrroles with 1,3,5-Triazines: Identification of Five Intermediates by <sup>1</sup>H, <sup>13</sup>C, <sup>15</sup>N, and <sup>19</sup>F NMR Spectroscopy
作者:Michael De Rosa、David Arnold
DOI:10.1021/jo8019626
日期:2009.1.2
5-triazine in THF-d8 to give a pyrrolo[2,3-d]pyrimidine was studied by 1H, 13C, 15N, and 19F NMR spectroscopy, and five intermediates were identified. A zwitterion was the first intermediate detected, and it cyclized to a tricyclic adduct and its conjugate acid. It also gave a neutral imine via a proton switch. The tricyclic adduct underwent a retro-Diels−Alder reaction, but the expected CF3CN was
1-叔丁基-2-氨基吡咯与2,4,6-三(三氟甲基)-1,3,5-三嗪在THF- d 8中的反电子需求Diels-Alder(IEDDA)反应,得到吡咯并[通过1 H,13 C,15 N和19 F NMR光谱研究了2,3- d ]嘧啶,并鉴定了5种中间体。两性离子是第一个被检测到的中间体,它被环化成三环加合物及其共轭酸。它还通过质子开关产生了中性的亚胺。三环加合物进行了逆Diels-Alder反应,但未检测到预期的CF 3 CN。NMR表明2-氨基吡咯的氨基键合到CF上。3 CN形成三氟乙酰氨基din离子。Retro-Diels-Alder反应的产物彼此迅速反应,得到最终的中间体。酸催化的loss的损失得到最终的芳族产物。这是第一项研究,其中获得了有关1,3,5-三嗪与含氨基的亲二烯体的IEDDA级联反应步骤顺序的直接实验证据。这项研究和类似的1,3-偶极环加成反应(已检测到或提出了两性离