Rhodium-Catalyzed Si–H Bond Insertion Reactions Using Functionalized Alkynes as Carbene Precursors

Abstract

Enantioselective transition-metal-catalyzed carbene insertion into Si–H bonds is a promising method for preparing chiral organosilicons; however, all the carbene precursors used to date in this reaction have been diazo compounds, which significantly limits the structural diversity of the resulting chiral organosilicons. Herein, we report a protocol for rhodium-catalyzed asymmetric Si–H bond insertion reactions that use functionalized alkynes as carbene precursors. With chiral dirhodium tetracarboxylates as catalysts, the reactions of carbonyl-ene-ynes and silanes smoothly gave chiral organosilanes in high yields (up to 98%) with excellent enantioselectivity (up to 98% ee). Kinetic studies suggest that insertion of the in situ-generated rhodium carbenes into the Si–H bonds of the silanes is probably the rate-determining step. This work represents the first enantioselective Si–H bond insertion reaction using alkynes as carbene precursors and opens the door for preparing chiral organosilicons with unprecedented structural diversity from readily available alkynes.

Transition Metal Catalyzed Insertion Reactions with Donor/Donor Carbenes

“…Outside of C−H insertion reactions, Zhu found that these diazo‐free donor and donor/donor carbenes generated from enynones are productive in N−H, O−H, and Si−H insertion reactions, in addition to cyclopropanation reactions with gold N‐heterocylic carbene catalyst 35 (Figure 17). [81] In a more recent report, Zhu and co‐workers (Nankai University) used rhodium paddlewheel complexes with these enynone derived diazo‐free carbenes to achieve enantioselective Si−H insertion for a wide selection of substrates (Figure 17, 150 ) [82] …”

“…[81] In am ore recent report, Zhu and co-workers (Nankai University) used rhodium paddlewheel complexes with these enynone derived diazo-free carbenes to achieve enantioselective Si À Hi nsertion for aw ide selection of substrates (Figure 17, 150). [82] Echavarren and co-workers were able to generate diazofree donor carbenes through aretro-Büchner ring expansion (Figure 18). With gold phosphine catalyst 36,i ntramolecular C À Hi nsertion to form an indane was achieved as the minor product, affording mostly cyclopropanation products.…”

Linear One-Dimensional Coordination Polymers Constructed by Dirhodium Paddlewheel and Tetracyanido-Metallate Building Blocks

“…Dinuclear complexes with a paddlewheel structure show a rich chemistry and different electronic configurations as a consequence of the distribution of the energy levels and the number of electrons in the dimetallic unit [1,2]. Dirhodium complexes and, in particular, the tetracarboxylato derivatives, are among the most important and versatile paddlewheel compounds [1,2], and their reactivity has been explored in several fields such as catalysis [3][4][5][6][7][8][9] or bioinorganic chemistry [10][11][12][13]. The ground state electron configuration for most of these complexes is σ 2 π 4 δ 2 δ* 2 π* 4 for a diamagnetic Rh 2 4+ unit, which, therefore, displays a single metal-metal bond order [1,2].…”

Recent Advances in Iron‐Catalyzed Chemical and Enzymatic Carbene‐Transfer Reactions

“…However, a notable attention has been paid to Si−H carbene insertion reaction in last few years [36] . In this context, a number of transition metal catalysts such as Rh, Ru, Cu, Ir and Fe have been developed to catalyze this transformation [36,37] …”