Efficient Rhodium‐Catalyzed Multicomponent Reaction for the Synthesis of Novel Propargylamines. Issue 49 (22nd October 2015)

• Record Type: Journal Article
• Authors: Rubio‐Pérez, Laura; Iglesias, Manuel; Munárriz, Julen; Polo, Victor; Pérez‐Torrente, Jesús J.; Oro, Luis A.
• Is Part Of: Chemistry. Volume 21:Issue 49(2015)
• Page Start: 17701
• Page End: 17707
• Publication Date: 2015-10-22
• Subjects: CH activation -- hydroalkynylation -- multicomponent reactions -- propargylamines -- rhodium; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201502993
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: [{Rh(μ‐Cl)(H)2 (IPr)}2 ] (IPr = 1, 3‐bis‐(2, 6‐diisopropylphenyl)imidazole‐2‐ylidene) was found to be an efficient catalyst for the synthesis of novel propargylamines by a one‐pot three‐component reaction between primary arylamines, aliphatic aldehydes, and triisopropylsilylacetylene. This methodology offers an efficient synthetic pathway for the preparation of secondary propargylamines derived from aliphatic aldehydes. The reactivity of [{Rh(μ‐Cl)(H)2 (IPr)}2 ] with amines and aldehydes was studied, leading to the identification of complexes [RhCl(CO)IPr(MesNH2 )] (MesNH2 = 2, 4, 6‐trimethylaniline) and [RhCl(CO)2 IPr]. The latter shows a very low catalytic activity while the former brought about reaction rates similar to those obtained with [{Rh(μ‐Cl)(H)2 (IPr)}2 ]. Besides, complex [RhCl(CO)IPr(MesNH2 )] reacts with an excess of amine and aldehyde to give [RhCl(CO)IPr{MesNCHCH2 CH(CH3 )2 }], which was postulated as the active species. A mechanism that clarifies the scarcely studied catalytic cycle of A3 ‐coupling reactions is proposed based on reactivity studies and DFT calculations. Abstract : Mix ′em together! A range of new propargylamines have been prepared by a multicomponent reaction catalyzed by [{Rh(μ‐Cl)(H)2 (IPr)}2 ] (IPr = 1, 3‐bis‐(2, 6‐diisopropylphenyl)imidazole‐2‐ylidene). This reaction utilises primary arylamines, aliphatic aldehydes, and triisopropylsilylacetylene as starting materials, because alternative synthetic methods are difficult to apply due to the instability of the corresponding imines. A catalytic cycle that sheds light on this scarcely studied mechanism is proposed based on theoretical calculations and experimental data.