Reaction of tetraazathiapentalene and thiadiazolopyrimidine derivatives with heterocumulenes: Cycloaddition and elimination reactions<i>via</i>hypervalent sulfur intermediates
Tetraazathiapentalene derivative 1 reacts with heterocumulenes such as diphenylketene (2) and 2-pyridylisothiocyanate (5) to give heterocycles 3, 6 and 7 with elimination of methylisothiocyanate. The reactions of thiadiazolopyrimidine derivatives 8a-b with ethoxycarbonyl isothiocyanate (9) and carbon disulfide (11) gives heterocycles 10 and 12 via thermal decomposition of 1:1 cycloadducts C and D which
Tetraazapentalenes (R = CH3 and CH2=CHCH2) reacted with isocyanates to give new types of tetraazapentalenes, (2) and (3). The compounds, 2 and 3 were also obtained by the reaction of isocyanates with thiadiazolopyrimidines.
Synthesis and Structure of 6,7-Dihydro-2,3-disubstituted 5<i>H</i>-2a-Thia(2<i>a</i>-<i>S</i><sup>IV</sup>)-2,3,4a,7a-tetraazacyclopent[<i>cd</i>]indene-1,4(2<i>H</i>,3<i>H</i>)-dithione
Symmetrical tetraazapentalene derivatives 5 and 6 were synthesized by a convenient one-pot reaction using lithium thioureide/phenacyl chloride/alkyl (or allyl) isothiocyanate system. Unsymmetrical tetraazapentalene derivatives 8 were prepared by the reaction of various isothiocyanates with thiadiazolopyrimidine derivatives 7 which were derived from symmetrical tetraazapentalene derivatives. The structure of 5c was determined by a single crystal X-ray diffraction.