Highly functionalized dispiro oxindole-pyrrolo[1,2-c]thiazole-piperidone hybrid: Synthesis, characterization and theoretical investigations on the regiochemistry.

The synthesis of highly functionalized dispiro oxindole–pyrrolo[1,2- c ]thiazole–piperidone hybrid has been achieved regioselectively employing microwave-assisted three-component 1,3-dipolar cycloaddition. Structural elucidation of the compound has been accomplished using NMR spectroscopy and further confirmed by single crystal X-ray crystallographic studies. The molecular structure of the compound crystallized in monoclinic, P 2 1 / c , a = 11.6182 (2) Å, b = 12.2466 (2) Å, c = 21.7061 (3) Å, β = 103.018 (1)°, V = 3009.04 (8) Å 3 , Z = 4. The cycloaddition was found to proceed by normal electronic demand (NED) character with a significant high charge transfer (0.1247 eV) from the 1,3-dipole to the dipolarophile. The regiochemistry has been explained using the local reactivity descriptors obtained from the DFT calculations. The DFT optimized molecular structure agreed well with the X-ray results. [ABSTRACT FROM AUTHOR]