Selective carbonylation of benzene to benzaldehyde using a phosphorus–nitrogen PN3P–rhodium(i) complex?

Organic Chemistry Frontiers Pub Date: 2018-11-07 DOI: 10.1039/C8QO00892B

Abstract

A PN3P pincer ligand (1) bearing dicyclopentylphosphine substituents reacts with [Rh(COD)Cl]2 (COD = 1,5-cyclooctadiene) to produce the complex (PN3P)RhCl (2). Treatment of a benzene solution of 2 with KN(SiMe3)2 stimulates a dearomatization process, and C–H activation of benzene is achieved through the rearomatization of the central pyridine ring. This deprotonation/reprotonation of the NH arm of 2 gives the phenyl complex (PN3P)Rh(C6H5) (3). The subsequent introduction of CO gas into 3 yields the benzoyl complex (PN3P)RhCO (C6H5) (4), which can release benzaldehyde upon treatment with diluted HCl solution and regenerates 2.

Graphical abstract: Selective carbonylation of benzene to benzaldehyde using a phosphorus–nitrogen PN3P–rhodium(i) complex
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