| Abstract
| - Deprotonation of benzoxazole, benzothiazole, benzo[b]thiophene, benzo[b]furan, N-Boc-protected indoleand pyrrole, and N-phenylpyrazole using an in situ mixture of ZnCl2·TMEDA (0.5 equiv) and lithium2,2,6,6-tetramethylpiperidide (1.5 equiv) in THF at room temperature is described. The reaction wasevidenced by trapping with iodine, regioselectively giving the expected functionalized derivatives in52−73% yields. A mixture of mono- and disubstituted derivatives was obtained starting from thiazole.Cross-coupling reactions of 2-metalated benzo[b]thiophene and benzo[b]furan with heteroaromatic chloridesproved possible under palladium catalysis. A reaction pathway where the lithium amide and zinc diamidepresent in solution behave synergically was proposed for the deprotonation reaction, taking account ofNMR and DFT studies carried out on the basic mixture.
|
