Synthesis and Enzymatic Evaluation of a Small Library of Substituted Phenylsulfonamido-Alkyl Sulfamates towards Carbonic Anhydrase II

A small library of 79 substituted phenylsulfonamidoalkyl sulfamates, 1b-79b, was synthesized starting from arylsulfonyl chlorides and amino alcohols with different numbers of methylene groups between the hydroxyl and amino moieties yielding intermediates 1a-79a, followed by the reaction of the latter with sulfamoyl chloride. All compounds were screened for their inhibitory activity on bovine carbonic anhydrase II. Compounds 1a-79a showed no inhibition of the enzyme, in contrast to sulfamates 1b-79b. Thus, the inhibitory potential of compounds 1b-79b towards this enzyme depends on the substituent and the substitution pattern of the phenyl group as well as the length of the spacer. Bulkier substituents in the para position proved to be better for inhibiting CAII than compounds with the same substituent in the meta or ortho position. For many substitution patterns, compounds with shorter spacer lengths were superior to those with long chain spacers. Compounds with shorter spacer lengths performed better than those with longer chain spacers for a variety of substitution patterns. The most active compound held inhibition constant as low as Ki = 0.67 μM (for 49b) and a tert-butyl substituent in para position and acted as a competitive inhibitor of the enzyme.

Insight into the dual action mechanism of 3V-PPh3 polymers as carriers and ligands in the Rh/3V-PPh3 heterogeneous catalytic hydroformylation of ethylene to propionaldehyde

An experimentally confirmed porous vinyl-functionalized PPh₃ (3V-PPh₃) polymer-supported Rh-based catalyst exhibits the significant advantages of high activity, high stability, and easy separation in the synthesis of propionaldehyde, which fundamentally solves the problem of Rh precious-metal loss. In this paper, the microscopic mechanism and electronic structure characteristics of two kinds of cross-linked 3V-PPh₃ polymer-supported Rh-based catalyst were studied by means of quantum chemistry (QC). With 3V-PPh₃ as the carrier, stable adsorption configurations of Rh and 3V-PPh₃ were investigated, and the results showed that Rh and P had the strongest effects, while the vinyl group enhanced the adsorption strength of Rh. Moreover, it was found that a high concentration of exposed P was beneficial to the dispersion of Rh. With 3V-PPh₃ as the ligand, the properties of the HRh(CO)(P-frame)₃ complex were investigated, and the results of structure analysis indicated that there were strong interactions between Rh and P, which contributed more to the non-loss of Rh. Among the four different configurations, the Rh-P coplanar configuration of cross-linking mode 2 had the highest Rh-P bond energy. The results of AIM analysis suggested that the Rh-P and Rh-C(CO) bonds involve closed-shell (donor-acceptor) interactions. The Mulliken charge and molecular electrostatic potential results revealed that the Rh activity of the Rh and P non-coplanar configuration was higher in the two cross-linking methods. Hopefully, this work will clarify the structure-activity relationship between 3V-PPh₃ polymer and Rh, and provide theoretical guidance for the design and development of high-efficiency heterogeneous catalysts for the hydroformylation of ethylene to propionaldehyde.

Rh Particles Supported on Sulfated g-C3N4: A Highly Efficient and Recyclable Heterogeneous Catalyst for Alkene Hydroformylation

The hydroformylation of alkenes with CO and H2 to manufacture aldehydes is one of the most large-scale chemical reactions. However, an efficient and recyclable heterogeneous catalyst for alkene hydroformylation is extremely in demand in academia and industry. In this study, a sulfated carbon nitride supported rhodium particle catalyst (Rh/S-g-C3N4) was successfully synthesized via an impregnation-borohydride reduction method and applied in the hydroformylation of alkenes. The catalysts were characterized by XRD, FTIR, SEM, TEM, XPS, and nitrogen adsorption. The influence of the sulfate content, pressure of syngas, temperature, and reaction time, as well as the stability of Rh/S-g-C3N4, on the hydroformylation was examined in detail. The delocalized conjugated structure in g-C3N4 can lead to the formation of electron-deficient aromatic intermediates with alkenes. The sulphate g-C3N4 has a defected surface owing to the formation of oxygen vacancies, which increased the adsorption and dispersion of RhNPs on the surface of g-C3N4. Therefore, Rh/S-g-C3N4 exhibited an outstanding catalytic performance for styrene hydroformylation (TOF = 9000 h−1), the conversion of styrene could reach 99.9%, and the regioselectivity for the branched aldehyde was 52% under the optimized reaction conditions. The catalytic properties of Rh/S-g-C3N4 were also studied in the hydroformylation of various alkenes and displayed an excellent catalytic performance. Furthermore, the reuse of Rh/S-g-C3N4 was tested for five recycling processes, without an obvious decrease in the activity and selectivity under the optimum reaction conditions. These findings demonstrated that Rh/S-g-C3N4 is a potential catalyst for heterogeneous hydroformylation.

Boron modified TiO2 nanotubes supported Rh-nanoparticle catalysts for highly efficient hydroformylation of styrene

Boron modified TiO₂ nanotubes supported Rh-nanoparticle is created as a highly efficient catalyst for hydroformylation of styrene.

Designing highly efficient Rh/CPOL-bp&PPh3 heterogenous catalysts for hydroformylation of internal and terminal olefins

Vinyl functionalized Biphephos ligand, denoted as vinyl biphephos, has been succesfully synthesized.

Efficient Domino Hydroformylation/Benzoin Condensation: Highly Selective Synthesis of α-Hydroxy Ketones

An improved domino hydroformylation/benzoin condensation to give α-hydroxy ketones has been developed. Easily available olefins are smoothly converted into the corresponding α-hydroxy ketones in high yields with excellent regioselectivities. Key to success is the use of a specific catalytic system consisting of a rhodium/phosphine complex and the CO2 adduct of an N-heterocyclic carbene.