A heteroditopic NHC and phosphine ligand supported ruthenium(ii)-complex: an effective catalyst for the N-alkylation of amides using alcohols. Issue 12 (18th May 2022)

• Record Type: Journal Article
• Authors: Donthireddy, S. N. R.; Singh, Vivek Kumar; Rit, Arnab
• Is Part Of: Catalysis science & technology. Volume 12:Issue 12(2022)
• Page Start: 4050
• Page End: 4056
• Publication Date: 2022-05-18
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/d2cy00544a
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : A heteroditopic Ru(ii )-bis-NHC complex in combination with dppe was developed as an effective catalyst system (0.2 mol% loading) for the N -alkylation of amides and selective mono-/di-alkylation of 4-aminobenzamide derivatives in excellent yields. Abstract : A ruthenium(ii ) complex of a chelated heteroditopic N -heterocyclic carbene ligand in combination with a phosphine ligand was uncovered to be a highly effective catalyst for the N -alkylation of diverse amides using readily available primary alcohols. A wide range of secondary amides was thus obtained in excellent yields (up to 98%) employing a low catalyst (2c ) loading of 0.2 mol% and a substoichiometric amount of base. The 1 H NMR and ESI-MS analyses support the participation of a N -heterocyclic carbene and phosphine supported Ru–H species in the catalytic cycle and the mechanistic studies including the deuterium labelling experiment suggest the involvement of a borrowing hydrogen protocol. Additionally, the present catalytic system was also revealed to be efficient for the selective mono-alkylation and unsymmetrical di-alkylation of 4-aminobenzamides which have not been studied before to the extent of our knowledge.