Lianyue Wang

Selective oxidation of unsaturated alcohols catalyzed by sodium nitrite and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone with molecular oxygen under mild conditions.

We have developed a simple and practical process for the oxidation of alcohols to the corresponding carbonyl compounds by using a low catalytic amount of DDQ, NaNO(2) as a cocatalyst, and molecular oxygen as terminal oxidant. Nitric oxide generated in situ by NaNO(2) in the presence of AcOH is essential for the realization of the catalytic cycle at room temperature. The practical utility of this catalytic process has been demonstrated in the gram-scale oxidation of cinnamyl alcohol.

Asymmetric Epoxidation of Alkenes Catalyzed by a Porphyrin-Inspired Manganese Complex

A novel strategy for catalytic asymmetric epoxidation of a wide variety of olefins by a porphyrin-inspired chiral manganese complex using H2O2 as a terminal oxidant in excellent yield with up to greater than 99% ee has been successfully developed.

Asymmetric Oxidation Catalysis by a Porphyrin-Inspired Manganese Complex: Highly Enantioselective Sulfoxidation with a Wide Substrate Scope

The first genuinely promising porphyrin-inspired manganese-catalyzed asymmetric sulfoxidation method using hydrogen peroxide has been successfully developed, allowing for rapidly oxidizing (0.5-1.0 h) a wide variety of sulfides in high yields with excellent enantioselectivities (up to >99% ee).

Direct imine formation by oxidative coupling of alcohols and amines using supported manganese oxides under an air atmosphere

Manganese oxides loaded on various supports have been prepared and studied for the direct imine formation by oxidative coupling of alcohols and amines. Among the catalysts, hydroxyapatite supported manganese oxides (MnOx/HAP) show the best activity and selectivity for this reaction in the absence of an additional base using air as the environmentally benign terminal oxidant. NH3-/CO2-TPD results show that the amphoteric properties of MnOx/HAP are crucial for this reaction to obtain a satisfactory yield. Various aromatic alcohols and amines are smoothly transformed into the corresponding imines in good to excellent yields. The catalyst is reusable and gives 98% yield of the product in all 9 reuse tests. Compared with the fresh catalyst, the XRD and SEM of the reactivated MnOx/HAP after nine reactions do not show any obvious change.

Facile and efficient gold-catalyzed aerobic oxidative esterification of activated alcohols

A facile and efficient methodology is presented for the direct oxidative esterification of alcohols with alcohols catalyzed by NaAuCl4. Just in the presence of a low catalytic amount of base additive, the newly developed catalytic system proceeds with high selectivity and broad substrate scope under mild conditions with dioxygen or air as the environmentally benign terminal oxidant. Various alcohols including benzylic and allylic alcohols were smoothly reacted with methanol and even with long-chain aliphatic alcohols, affording the desired products in good to excellent yields (up to 95% yield). The present system showed high catalytic activity with a TOF up to 219 h−1. Kinetic studies of the reaction process provide fundamental insights into the catalytic pathway, and a possible reaction pathway was proposed based on the results of the control experiments. XPS, TEM, and UV-vis were carried out to characterize the chemical state of the Au catalyst in the present catalytic system. The results indicate that the Au nanoparticles were generated in situ and supported on K2CO3, forming a simple, recyclable and selective catalyst system for the direct oxidative esterification of alcohols.

Iron/ABNO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones under Ambient Atmosphere

We report a new Fe(NO3)3·9H2O/9-azabicyclo[3.3.1]nonan-N-oxyl catalyst system that enables efficient aerobic oxidation of a broad range of primary and secondary alcohols to the corresponding aldehydes and ketones at room temperature with ambient air as the oxidant. The catalyst system exhibits excellent activity and selectivity for primary aliphatic alcohol oxidation. This procedure can also be scaled up. Kinetic analysis demonstrates that C-H bond cleavage is the rate-determining step and that cationic species are involved in the reaction.

A Porphyrin-Inspired Iron Catalyst for Asymmetric Epoxidation of Electron-Deficient Olefins

An in situ formed porphyrin-inspired iron complex that catalyzes asymmetric epoxidation of di- and trisubstituted enones is described. The reaction provides highly enantioenriched α,β-epoxyketones (up to 99% ee). The practical utility of the new catalyst system is demonstrated by the gram-scale synthesis of optically pure epoxide. Hammett analysis suggests that the transition state of the reaction is electron-demanding and the active oxidant is electrophilic.

Asymmetric Epoxidation of Olefins with Hydrogen Peroxide by an in Situ-Formed Manganese Complex

Asymmetric epoxidation of a variety of cis, trans, terminal, and trisubstituted olefins in excellent yields (up to 94%) and enantioselectivities (>99% ee) by an in situ-formed manganese complex using H2O2 has been developed. A relationship between the hydrophobicity of the catalyst imposed by ligand and the catalytic activity has been observed. The influence of the amount and identity of the acid additive was examined, and improved enantioselectivities were achieved through the use of a catalytic amount of a carboxylic acid additive.

Enantioselective oxidation of sulfides with H2O2 catalyzed by a pre-formed manganese complex

A facile and environmentally friendly method is presented for the asymmetric oxidation of sulfides with H2O2, utilizing a pre-formed manganese complex. Just in the presence of a low catalytic amount of carboxylic acid (CA), a variety of sulfide substrates, including aryl alkyl, aryl benzyl and cyclic sulfides, reacted to form chiral sulfoxides in high yields (up to 95%) and excellent enantioselectivities (>99% ee) under mild conditions. Moreover, the practical utility of the method has been demonstrated by the synthesis of esomeprazole and albendazole sulfoxide (ABZO).

Synergistic H4NI–AcOH Catalyzed Oxidation of the Csp3–H Bonds of Benzylpyridines with Molecular Oxygen

The oxidation of benzylpyridines forming benzoylpyridines was achieved based on a synergistic H4NI-AcOH catalyst and molecular oxygen in high yield under solvent-free conditions. This is the first nonmetallic catalytic system for this oxidation transformation using molecular oxygen as the oxidant. The catalytic system has a wide scope of substrates and excellent chemoselectivity, and this procedure can also be scaled up. The study of a preliminary reaction mechanism demonstrated that the oxidation of the Csp(3)-H bonds of benzylpyridines was promoted by the pyridinium salts formed by AcOH and benzylpyridines. The synergistic effect of H4NI-AcOH was also demonstrated by control experiments.