Dearomative Michael addition involving enals and 2-nitrobenzofurans realized under NHC-catalysis

In the manuscript the first enantioselective dearomative Michael addition between α,β-unsaturated aldehydes and 2-nitrobenzofurans realized under N-heterocyclic carbene activation has been described. The reaction proceeds via addition of homoenolate to Michael acceptors leading to the formation of biologically important heterocycles with high yields and stereoselectivities. Their functionalization potential has been confirmed in selected, diastereoselective transformations.

New Bicyclic Azalide Macrolides Obtained by Tandem Palladium Catalyzed Allylic Alkylation/Conjugated Addition Reaction

Unprecedented tandem allylic alkylation/intermolecular Michael addition was used in the preparation of novel bicyclic azalides. NMR spectroscopy was used not only to unambiguously determine and characterize the structures of these unexpected products of chemical reaction but also to investigate the effect the rigid bicyclic modification has on the conformation of the whole molecule. Thus, some of the macrolides prepared showed antibacterial activity in the range of well-known antibiotic drug azithromycin.

Highly Enantioselective Michael Addition of Cyclic Diketones to β,γ-Unsaturated α-Keto Esters Catalyzed by Squaramide Organocatalyst

A new tertiary amine-squaramide organocatalyst has been developed and applied to the asymmetric Michael addition of cyclic diketones to β,γ-unsaturated α-keto esters. The catalyst system performed well with a low catalyst loading of 1 mol% under mild reaction conditions. A series of synthetically and pharmaceutically useful chiral bicyclic compounds were obtained in high yields (up to 97%) with excellent enantioselectivities (up to 99 % ee). Furthermore, this catalytic system can be used efficiently in large-scale reactions with the yields and enantioselectivities being maintained.

Solvent Dependent Activity of Candida Antarctica lipase B and its Correlation with a Regioselective Mono Aza-Michael Addition- Experimental and Molecular Dynamics Simulation Studies

With the aim of gaining understanding of the molecular basis of Candida antarctica lipase B (CALB) catalyzed regioselective mono aza-Michael addition of Benzhydrazide to Diethyl maleat (DEM) we decided to carry out molecular dynamics (MD) simulation studies in parallel with our experimental study. We found a correlation between the activity of CALB and the choice of solvent. Our study showed that solvent affects the performance of the enzyme due to the binding of solvent molecules to the enzyme active site region, and the solvation energy of substrates in the different solvents. We found that CALB is only active in nonpolar solvent (i.e. Hexane), and therefore we investigated the influence of Hexane on the catalytic activity of CALB for the reaction. The results of this study and related experimental validation from our studies have been discussed here.

Organo-catalysis as emerging tools in organic synthesis: aldol and Michael reactions

Organocatalysis has occupied sustainable position in organic synthesis as a powerful tool for the synthesis of enantiomeric-rich compounds with multiple stereogenic centers. Among the various organic molecules for organocatalysis, the formation of carbon–carbon is viewed as a challenging issue in organic synthesis. The asymmetric aldol and Michael addition reactions are the most significant methods for C–C bond forming reactions. These protocols deliver a valuable path to access chiral molecules, which are useful synthetic hybrids in biologically potent candidates and desirable versatile pharmaceutical intermediates. This work highlighted the impact of organocatalytic aldol and Michael addition reactions in abundant solvent media. It focused on the crucial methods to construct valuable molecules with high enantio- and diastereo-selectivity.