Jayasree Seayad

Rhodium(III)-Amine Dual Catalysis for the Oxidative Coupling of Aldehydes by Directed C–H Activation: Synthesis of Phthalides

A novel oxidative coupling of aldehydes to form C3-substituted phthalides facilitated by co-operative dual catalysis of a Rh(III) complex and an aryl amine is reported. The reaction involves a cascade ortho C-H activation-insertion-annulation sequence. This methodology is efficient and applicable for the homo- and heterocoupling of various functionalized aldehydes generating the corresponding phthalides in moderate to high yields.

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.

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 .

Cardiomyocyte differentiation of pluripotent stem cells with SB203580 analogues correlates with Wnt pathway CK1 inhibition independent of p38 MAPK signaling

Differentiation of human pluripotent stem cells as embryoid bodies (EBs) has been achieved previously with p38alfa MAPK inhibitors such as SB203580 with moderate efficiency of 10-15%. We synthesized and screened 42 compounds that are 2,4,5-trisubstituted azole analogues of SB203580 for efficient cardiomyocyte differentiation. Our screen identified novel compounds that have similar cardiac differentiation activity as SB203580. However, the cardiac differentiation did not correlate with p38alfa MAPK inhibition, indicating an alternative mechanism in cardiac differentiation. Upon profiling several 2,4,5-trisubstituted azole compounds against a panel of 97 kinases we identified several off targets, among them casein kinases 1 (CK1). The cardiomyogenic activities of SB203580 and its analogues showed a correlation with post mesoderm Wnt/beta-catenin pathway inhibition of CK1 epsilon and delta. These findings united the mechanism of 2,4,5-trisubstituted azole with the current theory of Wnt/beta-catenin regulated pathway of cardiac differentiation. Consequently an efficient cardiomyocyte protocol was developed with Wnt activator CHIR99021 and 2,4,5-trisubstituted azoles to give high yields of 50-70% cardiomyocytes and a 2-fold increase in growth.

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.