Deprotonative Metalation of Five-Membered Aromatic Heterocycles Using Mixed Lithium−Zinc Species
作者:Jean-Martial L'Helgoual'c、Anne Seggio、Floris Chevallier、Mitsuhiro Yonehara、Erwann Jeanneau、Masanobu Uchiyama、Florence Mongin
DOI:10.1021/jo7020345
日期:2008.1.1
benzothiazole, benzo[b]thiophene, benzo[b]furan, N-Boc-protected indole and pyrrole, and N-phenylpyrazole using an in situ mixture of ZnCl2·TMEDA (0.5 equiv) and lithium 2,2,6,6-tetramethylpiperidide (1.5 equiv) in THF at room temperature is described. The reaction was evidenced by trapping with iodine, regioselectively giving the expected functionalized derivatives in 52−73% yields. A mixture of mono- and disubstituted
苯并恶唑,苯并噻唑,苯并[脱质子b ]噻吩,苯并[ b ]呋喃,Ñ -Boc保护的吲哚和吡咯和Ñ -phenylpyrazole在氯化锌的混合物原位使用2 ·TMEDA(0.5当量)和2,2-锂描述了室温下在THF中的1,6,6-四甲基哌啶(1.5当量)。通过捕获碘,区域选择性地以52-73%的收率选择性地提供了预期的官能化衍生物,证明了该反应。从噻唑开始获得单取代和二取代的衍生物的混合物。2-金属化苯并[ b ]噻吩与苯并[ b ]的交叉偶联反应在钯催化下,用杂芳族氯化物制备呋喃是可行的。考虑到对基本混合物进行的NMR和DFT研究,提出了一种溶液中存在的酰胺化锂和二酰胺化锌协同作用的反应途径。