Chlorine versus bromine: facial selectivity in the Diels–Alder reactions of 5-bromo-1,2,3,4,5-pentachlorocyclopenta-1,3-diene
作者:Lori C. Burry、David O. Miller、D. Jean Burnell
DOI:10.1039/a805355c
日期:——
Diels–Alder reactions of diene 11 with both electron-poor and electron-rich dienophiles led to approximately 90% addition to the face of 11 syn to the C-5 chlorine. Addition of 4-phenyl-1,2,4-triazoline-3,5-dione was slightly less facially selective. Adduct ratios were obtained by NMR methods; stereochemistry was determined by X-ray crystallography. The results support the view that facial selectivity
二烯11相导致了大约90%的除了面部11的两个贫电子和富电子的亲二烯体的Diels-Alder反应顺式到C-5是氯。添加4-苯基-1,2,4-三唑啉-3,5-二酮的面部选择性略低。通过NMR方法获得加合物比;立体化学通过X射线晶体学测定。结果支持这样一种观点,即在与杂原子取代的二烯进行的狄尔斯-阿尔德反应中,面部选择性主要受空间相互作用(而非立体电子相互作用)控制。