Abdul Majeed Seayad

Copper-Catalyzed Diacetoxylation of Olefins using PhI(OAc)2 as Oxidant

Copper(I) or -(II) salts with weakly coordinating anions catalyze the diacetoxylation of olefins efficiently in the presence of PhI(OAc)(2) as the oxidant under mild conditions. The reaction is effective for aryl, aryl alkyl, as well as aliphatic terminal and internal olefins forming the corresponding vicinal diacetoxy compounds in 70-85% yields and dr (syn/anti) of up to 5.2. Under these conditions, homoallylic alcohols formed the corresponding tetrahydrofuran derivatives in high yields.

Hydroaminomethylation of olefins using a rhodium carbene catalyst

Abstract Hydroaminomethylation of terminal as well as internal aliphatic and aromatic olefins with various amines is described in the presence of [Rh(cod)(Imes)Cl] as a catalyst. In general good to excellent yields and high chemoselectivity were obtained in THF at 85–105°C using 0.1 mol% of catalyst.

N-Heterocyclic Carbene (NHC) Catalyzed Cycloaddition of CO2 to N-Tosyl Aziridines: Regio and Stereoselective Synthesis of Oxazolidin-2-ones

In view of the world’s diminishing natural resources, the search for sustainable and renewable alternatives for chemicals, fuels, and materials is an ongoing challenge. In synthesis, the building blocks are carbon containing compounds that are derived either from nature or from petroleum feedstock. Thus, alternative, sustainable sources of carbon building blocks are highly coveted in chemical industries. One such possible alternative is the use of carbon dioxide as a one carbon source in synthesis. Carbon dioxide is abundantly available, renewable and is considered an environmentally friendly building block. Oxazolidinones are important heterocyclic compounds that are widely used as chiral auxiliaries and the oxazolidinone motif is present in many pharmaceutical, as well as fine chemical intermediates. In particular, 5-substituted oxazolidin-2-ones are frequently employed as biologically active compounds for pharmaceutical and agricultural uses. The cycloaddition of CO2 to aziridines (Scheme 1) or to aminoalcohols [6] is among the most attractive routes to oxazolidin-2-ones as compared to alternative processes that use the toxic and corrosive phosgene or CO .

Self‐Supported Chiral Titanium Cluster (SCTC) as a Robust Catalyst for the Asymmetric Cyanation of Imines under Batch and Continuous Flow at Room Temperature

A robust heterogeneous self-supported chiral titanium cluster (SCTC) catalyst and its application in the enantioselective imine-cyanation/Strecker reaction is described under batch and continuous processes. One of the major hurdles in the asymmetric Strecker reaction is the lack of availability of efficient and reusable heterogeneous catalysts that work at room temperature. We exploited the readily hydrolyzable nature of titanium alkoxide to synthesize a self-supported chiral titanium cluster (SCTC) catalyst by the controlled hydrolysis of a preformed chiral titanium-alkoxide complex. The isolated SCTC catalysts were remarkably stable and showed up to 98 % enantioselectivity (ee) with complete conversion of the imine within 2 h for a wide variety of imines at room temperature. The heterogeneous catalysts were recyclable more than 10 times without any loss in activity or selectivity. The robustness, high performance, and recyclability of the catalyst enabled it to be used in a packed-bed reactor to carry out the cyanation under continuous flow. Up to 97 % ee and quantitative conversion with a throughput of 45 mg h(-1) were achieved under optimized flow conditions at room temperature in the case of benzhydryl imine. Furthermore, a three-component Strecker reaction was performed under continuous flow by using the corresponding aldehydes and amines instead of the preformed imines. A good product distribution was obtained for the formation of amino nitriles with ee values of up to 98 %. Synthetically useful ee values were also obtained for challenging α-branched aliphatic aldehyde by using the three-component continuous Strecker reaction.

HOMOGENEOUS CATALYSIS: AN OVERVIEW

Catalysis plays an important role in our day-to-day life either directly or indirectly. While the petrochemical industries are largely based on catalytic processes, in recent decades, small volume specialty and fine chemicals and pharmaceuticals are increasingly produced through catalytic routes as part of effort to improve efficiencies of reactions. In this review, some of the important homogeneous catalytic methodologies relevant to the synthesis of value added products are described.