Reactions of Nitrile Oxides and Nitrile Imines with 4-Arylidene-2-phenyl-5(4H)-thiazolones
Nitrile oxides 2a, b and nitrile imines 2c-e are added to the C=C bond of 4-arylidene-2-phenyl-5(4H)-thiazolones 1 to afford spiro-isoxazolines 3a-d and spiro-pyrazolines 3e-j, respectively.The cycloaddition reactions are regioselective and only one of the two possible regioisomers is isolated.Reactions of the cycloadducts with nucleophiles lead to isoxazole and pyrazole derivatives 8 and 10 by opening of the thiazolone ring.