Ionic liquid accelerated multicomponent sequential assembly of ferrocene grafted spiro-heterocycles

A facile one-pot synthesis of novel ferrocene grafted spiro-indenoquinoxalline pyrrolizidines/pyrrolo[1,2-c]thiazole via multicomponent [3 + 2] cycloaddition of azomethine ylides using N-(1-acroloyl)-N-(4-cyclopentyl)-piperazinium dihydrogen phosphate as ionic liquid is described. The structure of cycloadducts were confirmed by IR, 1H NMR, 13C NMR, high resolution mass spectroscopy, single crystal X-ray analysis. The ionic liquid, N-(1-acroloyl)-N-(4-cyclopentyl)-piperazinium phosphate is easy to synthesize and more specific in providing the desired product with high regioselectivity, in much shorter reaction time, higher yield and no column purification of the product is required.