Abstract:Graphically revealing interaction regions in a chemical system enables chemists to notice the areas at a glance where significant interactions have formed, it is very helpful in studying chemical bonds, intermolecular and intramolecular interactions. Reduced density gradient (RDG) has already been widely employed in literatures to visually exhibit weak interaction regions, in fact it also has the ability of revealing chemical bonding regions. Unfortunately, RDG cannot clearly show both types of the interaction… Show more
“…First, comparison of the most dominant TS, 1ad_S and its "epimer" 1ad_R suggest that the major factor contributing to the energy difference is the appreciably larger distortion energy of the silane fragment in the latter, likely rising from shorter C-Si bond (2.19Å vs 2.27Å) and slightly longer Si-H bond (1.61Å vs 1.60Å). Interaction region indicator (IRI) analysis 71 (processed by Multiwfn 3.8 dev. 72 ) revealed the appreciable differences in non-covalent interaction regions: the former features a larger and stronger van der Waals (vdW) attraction region between the Si-Me moiety and one of the P-Ar of the ligand as compared to the latter (Scheme 1C, red circled part in i vs ii), which likely helps increase the interaction energy, while reduce the strain of the fragments.…”
Herein we report an unprecedented copper-catalyzed asymmetric anti-Markovnikov hydrosilylation of alkynes with dihydrosilanes for the synthesis of silicon-stereogenic alkenyl silanes in good regio- and enantioselectivities. Demonstrated by a diverse collection of substrates, the process grants access to chiral alkenylhydrosilanes with a simple Cu/(S)-Tol-BINAP catalytic system. The origin of the enantiocontrol was investigated by density functional theory (DFT) calculations, which revealed a quite complicated scenario involving multiple pairs of diastereomeric transition structures accounting for the high enantiocontrol under the seemingly simple conditions.
“…First, comparison of the most dominant TS, 1ad_S and its "epimer" 1ad_R suggest that the major factor contributing to the energy difference is the appreciably larger distortion energy of the silane fragment in the latter, likely rising from shorter C-Si bond (2.19Å vs 2.27Å) and slightly longer Si-H bond (1.61Å vs 1.60Å). Interaction region indicator (IRI) analysis 71 (processed by Multiwfn 3.8 dev. 72 ) revealed the appreciable differences in non-covalent interaction regions: the former features a larger and stronger van der Waals (vdW) attraction region between the Si-Me moiety and one of the P-Ar of the ligand as compared to the latter (Scheme 1C, red circled part in i vs ii), which likely helps increase the interaction energy, while reduce the strain of the fragments.…”
Herein we report an unprecedented copper-catalyzed asymmetric anti-Markovnikov hydrosilylation of alkynes with dihydrosilanes for the synthesis of silicon-stereogenic alkenyl silanes in good regio- and enantioselectivities. Demonstrated by a diverse collection of substrates, the process grants access to chiral alkenylhydrosilanes with a simple Cu/(S)-Tol-BINAP catalytic system. The origin of the enantiocontrol was investigated by density functional theory (DFT) calculations, which revealed a quite complicated scenario involving multiple pairs of diastereomeric transition structures accounting for the high enantiocontrol under the seemingly simple conditions.
“…The strong interactions are observed due to π-electrons conjunction within the aromatic ring i.e., for the C C link. Repulsion (steric effect) is exhibited for the C---O link and the Van der Waals interactions are found between the hydrogen and metal (Cu and Zn) atoms [ 30 ]. Fig.…”
“…Notably, although the metathesis of allenylcopper with PhSiH 3 via both 4-and 6-membered transition states are feasible, in the dppp ligated pathway, the four-membered transition state TS 4 dppp is lower in energy by 5.3 kcal/mol, likely due to the more favorable interaction energy (-46.6 kcal/mol) between the allenylcopper and silane moieties, as revealed by distortion interaction analysis, 78 to which the attractive dispersion interactions between P-aryl moieties of the ligand and the Ph group and the terminal C = CMe moiety on the allenylcopper play an important contribution, according to interaction region indicator analysis 79 (Fig. 3c, i).…”
We report a copper-catalyzed ligand-controlled selective 1,2- and 1,4-hydrosilylation of 1,3-enynes, which furnishes enantiomerically enriched propargyl- and 1,2-allenylsilane products in high yields with excellent enantioselectivities (up to 99% ee). This reaction proceeds under mild conditions, shows broad substrate scope for both 1,3-enynes and trihydrosilanes, and displays excellent regioselectivities. Mechanistic studies based on deuterium-labeling reactions and density functional theory (DFT) calculations suggest that allenylcopper is the dominant reactive intermediate under both 1,2- and 1,4-hydrosilylation conditions, and it undergoes metathesis with silanes via selective four-membered or six-membered transition state, depending on the nature of the ligand. The weak interactions between the ligands and the reacting partners are found to be the key controlling factor for the observed regioselectivity switch.
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