Rhodium-catalyzed asymmetric 1,4-addition reactions of aryl boronic acids with nitroalkenes: reaction mechanism and development of homogeneous and heterogeneous catalysts† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc03025h
نویسندگان
چکیده
Asymmetric 1,4-addition reactions with nitroalkenes are valuable because the resulting chiral nitro compounds can be converted into various useful species often used as chiral building blocks in drug and natural product synthesis. In the present work, asymmetric 1,4-addition reactions of arylboronic acids with nitroalkenes catalyzed by a rhodium complex with a chiral diene bearing a tertiary butyl amide moiety were developed. Just 0.1 mol% of the chiral rhodium complex could catalyze the reactions and give the desired products in high yields with excellent enantioselectivities. The homogeneous catalyst thus developed could be converted to a reusable heterogeneous metal nanoparticle system using the same chiral ligand as a modifier, which was immobilized using a polystyrene-derived polymer with cross-linking moieties, maintaining the same level of enantioselectivity. To our knowledge, this is the first example of asymmetric 1,4-addition reactions of arylboronic acids with nitroalkenes in a heterogeneous system. Wide substrate generality and high catalytic turnover were achieved in the presence of sufficient water without any additives such as KOH or KHF2 in both homogeneous and heterogeneous systems. Various insights relating to a rate-limiting step in the catalytic cycle, the importance of water, role of the secondary amide moiety in the ligand, and active species in the heterogeneous system were obtained through mechanistic studies.
منابع مشابه
Application of chiral N-tert-butylsulfinyl vinyl aziridines in Rh(I) catalyzed 1,4-addition of aryl boronic acids to cyclic enones.
Chiral N-tert-butylsulfinyl vinyl aziridine ligands prepared from a readily available (R)-tert-butanesulfinamide have been applied in the rhodium-catalyzed asymmetric 1,4-addition of aryl boronic acids to cyclic enones, which gives high yields and excellent enantioselectivities.
متن کاملRegio- and stereospecific rhodium-catalyzed allylic alkylation with an acyl anion equivalent: an approach to acyclic α-ternary β,γ-unsaturated aryl ketones† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc05705e Click here for additional data file.
متن کامل
Sequential catalysis: exploiting a single rhodium(i) catalyst to promote an alkyne hydroacylation–aryl boronic acid conjugate addition sequence† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc03066a Click here for additional data file.
We demonstrate that a single Rh(I) complex can promote two mechanistically distinct C–C bond-forming reactions – alkyne hydroacylation and aryl boronic acid conjugate addition – to deliver substituted ketone products from the controlled assembly of three readily available fragments. This is a rare example of a Rh(I)/Rh(III) cycle and a redox neutral Rh(I) cycle being promoted by a single cataly...
متن کاملDesign of N-cinnamyl sulfinamides as new sulfur-containing olefin ligands for asymmetric catalysis: achieving structural simplicity with a categorical linear framework.
The design and development of an extraordinarily interesting new class of chiral sulfur-olefin hybrid ligands with remarkable structural simplicity were described. These unique sulfinamide-olefin ligands have been proved to be highly effective ligands in rhodium-catalyzed asymmetric 1,4-addition reactions of aryl boronic acids to α,β-unsaturated carbonyl compounds (up to 99% yield and 98% ee).
متن کاملEnantioselective γ-borylation of unsaturated amides and stereoretentive Suzuki–Miyaura cross-coupling† †Electronic supplementary information (ESI) available: Catalyst optimization data; experimental procedures; compound characterization data; spectra. See DOI: 10.1039/c7sc01093a
The rhodium-catalyzed, directed catalytic asymmetric hydroboration of g,d-unsaturated amides affords a direct route to chiral acyclic secondary g-borylated carbonyl derivatives in high enantiomeric purity. In contrast to a similar b-borylated amide derivative, the g-borylated amide undergoes Suzuki–Miyaura cross-coupling with stereoretention. The utility of the boronic ester products is further...
متن کامل