Search

As a base structural unit, 1,4-dihydropyridines (DHPs) containing benzosultams widely exist in bioactive molecules and drugs. These compounds are generally synthesized by organic-base catalyzed methods that require specifically functionalized substrates or harsh conditions. Herein, a [3+3] annulation reaction of cyclic N-sulfonyl ketimine with various substituted isatylidene malononitrile or benzylidene malononitriles was documented. This biocatalytic strategy provides a green route for synthesis of 1,4-DHPs containing benzosultams, with good functional groups compatibility and yields. Under optimal conditions, lipase leads to the formation of 1,4-DHPs containing benzosultams in up to 87% yield. [ABSTRACT FROM AUTHOR]

The development of non-natural enzymatic catalysis is important for multicomponent tandem organic transformations. However, the delicate acting environments of biological enzymes still present some challenges in the synthesis of spirooxindole skeleton via enzymatic catalysis. To address these issues, a lipase-catalyzed method was developed for the synthesis of spirooxindole frameworks. Using easily available isatins, cycloketones, and malononitriles as substrates, mild reaction conditions, and a reasonable reaction time, moderate to good yields (67–92%) and excellent functional group tolerance were accomplished via this protocol. The related mechanism explanation is also speculated in this paper. [ABSTRACT FROM AUTHOR]

• Hemin is used as a highly efficient catalyst for the controlled synthesis of α-aminonitriles and α-iminonitriles. • High yields of the desired products were obtained with good functional group tolerance. • This work extends the application of Hemin in organic synthesis. We report an efficient and controlled oxidative cyanation approach for the synthesis of α-aminonitriles and α-iminonitriles in MeOH using Hemin (1 mol %) as a nontoxic and natural catalyst under room temperature. This work is the first report on the incorporation of a natural iron porphyrin complex as a redox catalyst for the oxidation of secondary amines. The significant features of this biomimetic strategy for the preparation of α-aminonitriles and α-iminonitriles include the use of MeOH as green and attractive solvent in an organic reaction, the use of ethyl cyanoformate as a benign cyanide source due to its mild conditions, environmentally friendly, the use of a biodegradable catalyst, no moisture sensitivity, simple workup procedure, and controllable, which all together make the current method attractive for academic research as well as industrial applications. [Display omitted] [ABSTRACT FROM AUTHOR]