A sequential multicomponent reaction (SMCR) strategy: Synthesis of novel pyrazolo-1,4-dioxaspiro[4,5]decane grafted spiro-indenoquinoxaline pyrrolidine heterocycles

A facile and expedient one-pot sequential five-component synthesis of highly substituted trispiro-pyrrolidine heterocycles is described. The key step involves [3 + 2]-cycloaddition of azomethine ylide. This multicomponent reaction (MCR) strategy provides a mild reaction condition, high yield of the products, high regioselectivity, and operational simplicity to assemble complex structural entity in a single operation. The structure of product was confirmed by IR, 1H-NMR, 13C-NMR, and high-resolution mass spectroscopic analysis. A theoretical insight is provided through MM2 calculation for the formation of the observed products