Convenient Construction of Spiro[pyrazole‐4,1′‐pyrido[2,1‐a]isoquinoline] and Spiro[pyrazole‐4,4′‐pyrido[1,2‐a]quinoline] via Three‐Component Reaction

Abstract

AbstractThe three‐component reaction of isoquinoline, dialkyl but‐2‐ynedioate and 4‐arylidene‐5‐methyl‐2‐phenylpyrazol‐3‐ones in acetonitrile at room temperature gave functionalized spiro[pyrazole‐4,1′‐pyrido[2,1‐a]isoquinolines] in satisfactory yields with cis/cis‐diastereoisomer as major product. On the other hand, the similar three‐component reaction with quinoline afforded both cis/cis‐ and cis/trans‐isomeric spiro[pyrazole‐4,4′‐pyrido[1,2‐a]quinolines] in nearly comparable yields. The reaction was finished with in situ generation of Huisgen’ 1,4‐dipole, sequential Michael addition and annulation reaction process.