Convenient synthesis of spiro-pyrazolone–pyrrolidinones via ipso-cyclization of arylidene pyrazolones with 2-chloro-N-phenylacetamides

Abstract

In this study, we present a convenient synthesis of spiro-pyrazolone–pyrrolidinones via NaH-mediated cascade ipso-cyclization of unsaturated pyrazolones with 2-chloro-N-phenylacetamides. This method offers an efficient route to a variety of highly functionalized spiro-pyrazolone–pyrrolidinones with good yields under transition metal-free conditions. This protocol features several advantages, including stable substrates, straightforward operational procedures, and both atom and step economy. Notably, the practical feasibility of this strategy has been demonstrated on a gram scale, yielding good product quantities.