One-pot domino synthesis of five- and six-membered fused dihydropyridines promoted by PPh3–NBS in aqueous medium?

Organic & Biomolecular Chemistry Pub Date: 2023-05-04 DOI: 10.1039/D3OB00472D

Abstract

A facile one-pot synthesis of five- and six-membered fused dihydropyridines such as chromenodihydropyridines, pyrazolodihydropyridines and isoxazolopyridines was accomplished for the first time by employing PPh3–NBS via a formal [3 + 2 + 1] cycloaddition of 1,3-bisnucleophiles (i.e., 2-aminochromone, 4-aminochromone, 5-aminopyrazole and 5-aminoisoxazole), β-enaminones and aldehydes in aqueous medium. The present approach involves a Michael type addition followed by intramolecular cyclization leading to the formation of two new C–C bonds and one C–N bond. High compatibility and excellent yields are the advantages of this protocol.

Graphical abstract: One-pot domino synthesis of five- and six-membered fused dihydropyridines promoted by PPh3–NBS in aqueous medium
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