Silylformylation of Chiral 1-Alkynes, Catalysed by Solvated Rhodium Atoms

Abstract

Solvated rhodium atoms, prepared by the metal vapour synthesis technique, promote the silylformylation reaction of variously substituted alkynes R 1 R 2 CH(CH 2 ) n CϵCH, with catalytic activities comparable with and even higher than more common species such as Rh 4 (CO) 12 . Z-Silylalkenals are exclusively formed in high yields (60−95%) indicating syn addition both of CO and of the silane (Me 2 PhSiH) to the triple bond. The chemoselectivity of the process (silylformylation vs. hydrosilylation) is highly affected by the amount of cata-

Cationic complexes of dirhodium(II) with 1,8-naphthyridine: Catalysis of reactions involving silanes

“…Compared with the previously reported cationic dirhodium(II) complexes with oxothioethers, we have obtained comparable conversions but much higher selectivities with the best catalysts presented in this work. Although not optimised, the catalytic performance of these complexes compares favourably with that of other rhodium-based catalysts such as dirhodium(II) perfluorobutyrate [4d,4e], Rh 4 (CO) 12 [15,16] or solvated rhodium atoms [15]. Thus, it can be stated that the presence of a positive charge on the dirhodium(II) catalyst does significantly promote the silylformylation reaction.…”

“…The reactor was pressurised with 10 atm CO and the mixture was stirred at room temperature for 6 h. After removal of excess CO (fume hood), the reaction mixture was diluted with pentane (10 mL), filtered on celite and concentrated under vacuum. The composition of the reaction mixture was determined by GLC, GC-MS and 1 H-NMR analysis [15].…”

Metal vapour derived supported rhodium nanoparticles in the synthesis of β-lactams and β-lactones derivatives

“…In particular the catalytic activity of Rh/C (MVS) was comparable to the Rh/mesitylene precursor solution and even higher than Rh 4 (CO) 12 (Table 2, entry 3 vs. entries 2 and 1), commonly used as homogeneous catalyst in this reaction [72].…”

“…After removal of excess CO (fume hood), the reaction mixture was diluted with pentane or CH 2 Cl 2 , filtered (Celite) and concentrated by bulb to bulb distillation (1 Torr). The residue was purified by column chromatography on silica gel affording the pure aldehydes [50,72].…”

“…Since the silylformylation is a common side reaction of the silylcarbocyclisation process, for this paper we started our investigation testing the activity of rhodium supported nanoparticles in the silylformylation of simple and functionalised acetylenes. As a matter of fact, we have previously described [72] that solvated rhodium atoms, prepared by the metal vapour synthesis technique, promoted the silylformylation reaction of variously substituted alkynes with catalytic activities comparable with and even higher than more common species such as Rh 4 (CO) 12 .…”