Synthesis and Thermal Reactivity of 2,2-Dioxo-3-Methyl-7-Trifluromethyl-1H,3H-Pyrrolo[1,2-c]thiazole

PELAEZ, WALTER JOSÉ; PEPINO, ANA JULIETA; ARGÜELLO, GUSTAVO; PINHO E MELO, T.M.V.D.

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2014 p. 2933 - 2933

he generation and reactivity of a novel 1-methyl-5-trifluoromethyl-azafulvenium methide is described. Under microwave induced pyrolysis this intermediate could be trapped by dipolarophiles acting as a 4π as well as 8π dipole. Quantum chemical calculations carried out at the DFT level of theory allowed the rationalization of the results observed in the cycloaddition of 1-methyl-5-trifluoromethyl-azafulvenium methide with N-substituted maleimides. The study revealed that for 1,7-cycloadducts, the major products are obtained in trans- configuration from the unusual exo-cycloaddition mode, while for 1,3-cycloadducts, the cis-counterparts are obtained from this unexpected approach. In addition, under flash vacuum pyrolysis or conventional thermolysis 1-methyl-5-trifluoromethyl-azafulvenium methide undergoes an allowed suprafacial sigmatropic [1,8]H shift leading to the formation of 2-methyl-3-trifluoromethyl-1vinyl-1H-pyrrole.