Efficient catalyst-free tricomponent synthesis of new spiro[cyclohexane-1,4′-pyrazolo[3,4-e][1,4]thiazepin]-7′(6′H)-ones

A series of spirocyclohexane-1,4 '-pyrazolothiazepinones were synthesized by one-pot multicomponent cyclocondensation reactions between 5-amino-1-arylpyrazoles, cyclohexanone and mercaptoacetic acid with good yields and easy purification protocols. Some control experiments involving isolation of reaction intermediates were performed leading to the proposal of three alternative mechanistic pathways conducting to the named spiroheterocycles. All target molecules were fully characterized by IR, NMR, melting point and HRMS. [GRAPHICS] .