Chemo- and Diastereoselective Synthesis of Pyrazolo-tetrahydropyridines via Multicomponent Sequential Aza-Diels-Alder Reactions in Water

In this study, we report a novel and an efficient strategy for the synthesis of chemo- and diastereoselective synthesis of pyrazolo-tetrahydropyridines via a one-pot multi-component intramolecular Aza-Diels-Alder reactions (ADARs) from benzoylacetonitrile derivatives, phenylhydrazine, salicylaldehyde derivatives, and styrenesulfonyl or cinnamoyl chloride in H2O as a green solvent. This synthesis procedure was also designed to follow the group-assisted purification (GAP) chemistry, which can avoid traditional purification such as recrystallization and chromatography methods.