Active template rotaxane synthesis through the Ni-catalyzed cross-coupling of alkylzinc reagents with redox-active esters. Issue 30 (25th June 2019)

• Record Type: Journal Article
• Authors: Echavarren, Javier; Gall, Malcolm A. Y.; Haertsch, Adrian; Leigh, David A.; Marcos, Vanesa; Tetlow, Daniel J.
• Is Part Of: Chemical science. Volume 10:Issue 30(2019)
• Page Start: 7269
• Page End: 7273
• Publication Date: 2019-06-25
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c9sc02457c
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : The Ni-catalyzed C(sp 3 )–C(sp 3 ) cross-coupling of redox-active esters and organozinc reagents is used for the active template synthesis of 'impossible' rotaxanes. Abstract : The synthesis of unsymmetrical axle [2]rotaxanes through a recently developed Ni-catalyzed C(sp 3 )–C(sp 3 ) cross-coupling of redox-active esters (formed directly from carboxylic acids) and organozinc reagents (derived from alkyl bromides) is reported. The method also furnishes, as a minor product, the symmetrical axle [2]rotaxanes resulting from the homo-coupling of the organozinc half-thread. The rotaxanes are formed in up to 56% yield with the ratio of unsymmetrical rotaxane increasing with the cavity size of the macrocycle. In the absence of the redox-active ester neither rotaxane is formed, even though the homo-coupling rotaxane product does not incorporate the redox-active ester building block. A Ni(iii ) intermediate is consistent with these observations, providing support for the previously postulated mechanism of the Ni-catalyzed cross-coupling reaction.