ISOTHIAZOLES .6. CYCLOADDITION OF AZIDES TO ISOTHIAZOLE DIOXIDES - SYNTHESIS OF THIADIAZABICYCLO[3.1.0]HEXENE DERIVATIVES AND THEIR THERMALREARRANGEMENT TO THIAZETE DIOXIDES, 1,2,6-THIADIAZINE DIOXIDES AND PYRAZOLES

3-Diethylamino-4-(4-methoxyphenyl)-isothiazole 1,1-dioxide(1) was made to react with arylalkyl- and arylazides 2. Cycloadducts 3, which coul d he isolated in some cases, afforded N-arylalkyl or N-aryl-thiadiazab icyclo[3.1.0]hexene derivatives 4 through N-2-elimination. Thermal rea rrangements of N-aryl- and N-beta-phenylethyl substituted compounds 4b -e, produced derivatives of 1,2-thiazete 1,1-dioxide 5, 1,2,6-thiadiaz ine 1,1-dioxide 6 and pyrazole 7. The reaction can be optimized to aff ord compounds 6 in synthetically useful yield. In the case of N-benzyl -thiadiazabicyclo[3.1.0]hexene derivative 4a the different substitutio n on the aziridine nitrogen produced a different reaction course, affo rding the thiadiazine derivative 6a and the pyrimidine derivative 8. C opyright (C) 1996 Elsevier Science Ltd