Sulfamic acid pyromellitic diamide-functionalized MCM-41 as a multifunctional hybrid catalyst for melting-assisted solvent-free synthesis of bioactive 3,4-dihydropyrimidin-2-(1H)-ones

This study introduces a practical approach to fabricate a novel hybrid acidic catalyst, namely sulfamic acid pyromellitic diamide-functionalized MCM-41 (MCM-41-APS-PMDA-NHSO₃H). Various techniques such as FTIR, TGA, XRD, BET, FESEM, and EDX were used to confirm its structural characteristics. The efficiency of the new MCM-41-APS-PMDA-NHSO₃H organosilica nanomaterials, as a heterogenous nanocatalyst, was examined in the synthesis of biologically active 3,4-dihydropyrimidin-2-(1H)-one derivatives under solvent-free conditions. It was found that the nanoporous MCM-41-APS-PMDA-NHSO₃H, demonstrating acidic nature and high surface area, can activate all the Biginelli reaction components to afford desired 3,4-dihydropyrimidin-2-(1H)-ones under solvent-free conditions in short reaction time. Furthermore, easy and quick isolation of the new introduced hybrid organosilica from the reaction mixture as well as its reusability with negligible loss of activity in at least five consecutive runs are another advantages of this green protocol.

Enzyme-catalysed one-pot synthesis of 4H-pyrimido[2,1-b] benzothiazoles and their application in subcellular imaging

Enzymes, which provide more efficient and eco-friendly strategies for various functional molecules' construction than traditional chemo-catalysts, were utilized for the synthesis of 4H-pyrimido[2,1-b] benzothiazole derivatives. Reported herein is a trypsin-catalysed three- component Biginelli reaction of aldehyde, β-ketoester and 2-amino benzothiazole in one pot, affording a streamlined pathway to diverse ring-fused pyrimidines. In addition to using commercially available aromatic aldehydes as substrates, acetaldehyde, the chemical liquid with rather low boiling point and difficult to handle above room temperature, is utilized to further extend the range of substrates. It was verified that most of the tested substrates exhibited satisfactory reactivity. In addition, several substrates indicated AIE (Aggregation-Induced Emission) property and have been investigated as potential biomarkers.

Bio-Catalysis in Multicomponent Reactions

Enzyme catalysis is a very active research area in organic chemistry, because biocatalysts are compatible with and can be adjusted to many reaction conditions, as well as substrates. Their integration in multicomponent reactions (MCRs) allows for simple protocols to be implemented in the diversity-oriented synthesis of complex molecules in chemo-, regio-, stereoselective or even specific modes without the need for the protection/deprotection of functional groups. The application of bio-catalysis in MCRs is therefore a welcome and logical development and is emerging as a unique tool in drug development and discovery, as well as in combinatorial chemistry and related areas of research.

Trypsin-catalyzed multicomponent reaction: A novel and efficient one-pot synthesis of thiazole-2-imine derivatives

The first Trypsin from porcine pancreas catalyzed a novel one-pot three-component reaction of α-bromoketone, primary alkylamines, and phenylisothiocyanate for the synthesis of thiazole-imine derivatives with high yields (up to 98%) in a short time under mild conditions. The results revealed that Trypsin exhibited excellent catalytic activity and great tolerance for broad substrates. This Trypsin-catalyzed three component convergent method provides a novel strategy for the synthesis of thiazole-2-imine derivatives and expands the promiscuous functions of enzymes in organic synthesis.

Recent Advances in Biocatalytic Promiscuity: Hydrolase-Catalyzed Reactions for Nonconventional Transformations

Enzymes have emerged in recent decades as ideal catalysts for synthetic transformations under mild reaction conditions. Their capacity to accelerate a myriad of biotransformations with high levels of selectivity and broad substrate specificity including excellent atom economy has led to a current full recognition. The six classes of enzymes (oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases) possess outstanding abilities to perform specific modifications in target molecules. Nevertheless, in the last fifteen years, novel examples have appeared related to nonconventional processes catalyzed by various classes of biocatalysts. Amongst these, hydrolases have received special attention since they display remarkable activities in initially unexpected reactions such as carbon-carbon and carbon-heteroatom bond-formation reactions, oxidative processes and novel hydrolytic transformations. In this review, the main findings in this area will be disclosed, highlighting the catalytic properties of hydrolases not only to catalyze single processes but also multicomponent and tandem nonconventional reactions.