cis-disulfoxide 4, or -1,1,5,5_tetraoxide: disulfone 6 can be accomplished with potassium permanganate and a phase transfer catalyst in a two phase system in 66% yield, with sodium metaperiodate in aqueous methanol in 95% yield, or ruthenium tetraoxide in 70% yield, respectively. Oxidation of the known monosulfoxide 2 with potassium permanganate and a phase transfer catalyst in a two phase system also gave monosulfone 3 in 73% yield.
The corresponding -1,1,5-trioxide: sulfoxide-sulfone 5 was selectively prepared in quantitative yield by oxidation of the monosulfone 3 with sodium metaperiodate in aqueous methanol. The crystal and molecular structures, and conformations of naphtho[l,8-b,c]-1,5-dithiocinl,l-dioxide (3), -1,5-dioxide (4), -1,1,5_trioxide (5), and -1,1,5,5-tetraoxide (6) were determined by single crystal X-ray analysis.
These compounds crystallize in the monocl+c space group P2,,, with a-13.184(4)A, b-13.182(5)A, c-7.106(1)A, ,9-104.14( 5) , and Z-4, the orthorhombic space group Pbca with a-17.931(2)A, b-13.108(3)A, c-20.280(4)A, and Z-16, the monocli+c space group P21,, with a-9.298(1)A, b-10.264 (2)A, c-13.396(2)A, p-110.06(1) , and Z-4, and the orthorhombic space group Phca with a-12.258(3)A, b-9.997A, c-20.168A, and Z-8, respectively. The structures were solved by direct methods. Full-matrix least-squares refinement led to conventional R factors of 0.034, 0.046, 0.041, and 0.049, respectively. The conformations of the molecules in the solid state were distorted boat, boat with cis-diequatorial sulfoxide; boat with equatorial sulfoxide, and the unusual twist conformer, respectively.