Palladium-Catalyzed Reactions of [Et3NH]+ Salts of [(μ-RS)(μ-CO)Fe2(CO)6]− Anions with Iodo-Aromatic Compounds To Give the Corresponding Butterfly μ-Acyl Fe/S Cluster Complexes
摘要:
Interestingly, the intermediate salts A [Et3NH] (A = (mu-RS)(mu-CO)Fe-2(CO)(6); R = i-Pr, sec-Bu, cy-C6H11, p-MeC6H4) prepared from Fe-3(CO)(12), RSH, and Et3N were found to react in situ with iodobenzene or its substituted derivatives in the presence of the catalyst precursor Pd(PPh3)(4) to give the benzoyl type mu-acyl complexes (mu-RS)(mu-ArCO)Fe-2(CO)(6) (Ar = phenyl or substituted phenyl), whereas the in situ reactions of A [Et3NH] with iodo-substituted aromatic heterocycles under the same conditions afforded the corresponding heterocyclic type mu-acyl complexes (mu-RS)(mu-ArCO)Fe-2(CO)(6) (Ar = heterocyclic or benzoheterocyclic group). Particularly worth noting is that such Pd-catalyzed C-C bond cross-coupling reactions are the first examples of catalytic reactions regarding A [Et3NH] salts reported so far. In addition, all the prepared new mu-acyl complexes and the three new intermediate salts A [Et3NH] (R = i-Pr, sec-Bu, cy-C6H11) were isolated and structurally characterized, while a possible pathway for such type Pd-catalyzed reactions regarding A [Et3NH] salts is suggested.
An economical and scalable electrochemical protocol for regioselective 3C–H halogenation of indole derivatives is reported. This strategy provides access to a host of 3‐iodo‐, 3‐bromo‐, 3‐chloro‐, and 3‐thiocyanoindole derivatives under mild conditions using inexpensive (pseudo)halide salts as the sole reagent. No supplementary electrolyte salt is necessary.