DITHIATOPAZINE AND RELATED SYSTEMS - SYNTHESIS, CHEMISTRY, X-RAY CRYSTALLOGRAPHIC ANALYSIS AND CALCULATIONS

The synthesis and chemistry of dithiatopazine (11), a stable 1,2-dithietane system, are described. Theoretical studies with this novel system are also included. The synthesis of 11 was achieved via controlled photoirradiation of dithionolactone 10. Photolytic or thermal decomposition of 11 led to olefin 12, a conversion that could also be carried out by a variety of reagents. Triphenylphosphine treatment of 11 led to the loss of one sulfur and the formation of the rearranged products 18 and 19. Treatment of 11 with PhS- resulted in the formation of 25, whereas brief exposure to NaBH4 followed by trapping with Mel led to the novel episulfides 31a and 31b. Exposure of 11 to AgBF4-Et3SiH resulted in a novel skeletal rearrangement leading to compound 36. Dithiatopazine (11), served as a sulfur-transfer reagent converting, under thermal conditions, diene 41 to cyclic sulfides 42 and 43 and acetylene 44 to the novel systems 45 and 46. Kinetic studies on the thermal decomposition of 11 revealed an activation energy for this process of 26.3 kcal/mol. Several X-ray crystallographic analyses, including that on dithiatopazine (11) are included in this study. MM2 parameterization for dithietanes and subsequent molecular mechanics evaluation permits the conclusion that dithiatopazine is a remarkably rigid structure experiencing little conformational mobility. Quantum mechanical (PRDDO) calculations for various dithietane systems suggest the singular stability of dithiatopazine to arise from a combination of thermodynamic factors and internal energy redistribution. Finally, MM2 parameters for episulfides were derived to allow for a comparison between dithiatopazine and its episulfides and bis(methylthio) analogues. © 1993, IEEE. All rights reserved. © 1990, American Chemical Society. All rights reserved.