Tandem conjugate addition, decarboxylation and esterification/amidation of coumarin 3-carboxylic acid derivatives with pyrazolones have been developed.

A short and efficient multicomponent sequence for synthesizing fused novel polyheterocyclic chromeno spiro-pyrrolidine oxindoles via 1,3-dipolar cycloaddition reaction mediated by reactive azomethine ylides catalyzed by the Graphene Oxide (GO) is reported herein. This approach was utilized for synthesizing fused polyheterocyclic spiro-pyrrolothiazole and spiro-pyrrole oxindoles with yields ranging from good to excellent. A heterogeneous GO catalyst with an ultra-low catalytic loading of 0.05 wt% could proficiently catalyze the reaction without the formation of any side products and can also be visualized by the formation of solid mass in the reaction flask. The methodology is green in nature and the products were isolated by simple filtration without the use of any chromatographic techniques.

A highly efficient pot, atom, and step economic construction of pharmacologically potential structurally functionalized 1,4-dihydropyridines, quaternary centered C-3 functionalized spiro[indoline-3,4'-pyridines], and C-11 functionalized spiro[indeno[1,2-b]quinoxaline-11,4'-pyridines] via rose bengal photoredox catalysis under...

Concise and stereoselective synthesis of Hagen's Gland Lactones is achieved by employing vinylogous Mukaiyama type reaction, Epimerization followed by oxy-Michael addition reaction to form bicyclic lactone as key steps with 54% overall yield. The synthetic route is economical and scalable within 5 steps without use of any toxic metals. The methodology could be useful for the synthesis of natural products containing bicyclic lactones and tetra substituted THF ring. Figure 3. Retrosynthetic analysis of Hagen's gland lactones. Scheme 1. Synthesis of Hagen's gland Lactones.