REACTIONS OF N-SULFONYLALKYLAMINES WITH YNAMINES - FORMATION OF 2H-1,2-THIAZETE 1,1-DIOXIDES, NOVEL THIOKETENE S,S-DIOXIDE DIMERS, AND OTHER S,N-HETEROCYCLES

N-Sulfonylalkylamines 2a, b react with ynamines 3 to give primarily 2H -1,2-thiazete 1,1-dioxides 4. But, except for the 4-triphenylsilyl spe cies 4a, b, these products are unstable and undergo electrocyclic ring opening to very reactive amidinosulfenes 5, which are transformed int o different products, depending on the ynamine substituents R(2). The 1,3-dithietane 1,1,3,3-tetraoxide 8 is formed from N-sulfonylisopro-py lamine (2a) and the trimethylsily-substituted ynamine 3b via amidinosu lfene 5c and probably thioketene S,S-dioxide 7. On the other hand, (is opropylamidino)sulfene 5d dimerizes to the 2H-1,5,2-dithiazine 9 and a lso gives the [2 +4] cycloadducts 10a, 11a by reaction with 2a and yna mine 3c, respectively. In contrast, it was possible to trap phenyl-sub stituted amidinosulfenes 5e-h by addition of water or methanol.