Remote stereocontrol of chiral NHC metal complexes by stereodynamic Aib foldamers and application to enantioselective hydrosilylations

Abstract

A series of Aib4-imidazolium bromide salts have been prepared by alkylation of 1-substituted imidazole compounds with the corresponding α-aminoisobutyric acid foldamer. These salts are precursors for the synthesis of series of rhodium(I) complexes containing bulky oligomer and alkyl functionalized N-heterocyclic carbenes (NHCs). The novel rhodium(I) complexes [RhCl(COD)(NHC)] [COD = cyclooctadiene, NHC =1-R1-3-R2-imidazolin-2-ylidene; R1= Me, Ph, Mes; R2 = N3Aib4Et, Cbz-L-(αMeVal)Aib4Et], contain on one nitrogen a bulky alkyl substituent and on the other an Aib foldamer substituent. The catalytic activity of the Aib rhodium(I) complexes in the hydrosilylation of carvone with H2SiPh2 and terminal alkynes with HSiMe2Ph have been investigated, and the dependence on the N-terminal functional groups of the Aib foldamer portion has been determined.

Date of Award	31 Dec 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	John Gardiner (Supervisor) & Simon Webb (Supervisor)