Active template rotaxane synthesis through the Ni-catalyzed cross-coupling of alkylzinc reagents with redox-active esters

摘要: The synthesis of unsymmetrical axle [2]rotaxanes through a recently developed Ni-catalyzed C(sp3)–C(sp3) cross-coupling redox-active esters (formed directly from carboxylic acids) and organozinc reagents (derived alkyl bromides) is reported. method also furnishes, as minor product, the symmetrical resulting homo-coupling half-thread. rotaxanes are formed in up to 56% yield with ratio rotaxane increasing cavity size macrocycle. In absence ester neither formed, even though product does not incorporate building block. A Ni(III) intermediate consistent these observations, providing support for previously postulated mechanism reaction.