Cycloaddition reactions with thiazyl derivatives RSN (RF, on(CF3)2): formation of 2,5-dihydro-1λ4,2,4,6-thiatriazines

[4 + 2] addition reactions of the thiazyl derivatives FSN (1) and (CF3)2NOSN (4) to the 1,3-diazabutadiene Me2C6H3NC(C6H5)–NC(CF3)2 (3) give the corresponding 2,5-dihydro-1λ4,2,4,6-thiatriazines 3 and 5 in 67 and 76% yield, respectively. X-ray structures of 3 and 5 are reported.