From a Stannene and Quinones to Various Tin-Containing Heterocycles

Some fused tin-containing heterocycles were prepared from the novel thermally stable stannene Tip2SnCR2 (1; Tip = 2,4,6-triisopropylphenyl, CR2 = 2,7-di-tert-butylfluorenylidene) and a series of quinones. Reaction of 1 with 1,4-benzoquinone afforded the unexpected conjugated 1,4-distannoxy-1,3-cyclohexadiene 2, according to a double [2+3] cycloaddition. In contrast, in 1,4-naphthoquinone and 9,10-anthraquinone the aromatic ring fused to the quinonic moiety was involved in the reaction, leading to hexahydrodioxadistannapyrene 3 and hexahydrodioxadistannabenzopyrene 4. Ortho-quinones, such as 9,10-phenanthrenequinone, gave by [2+4] cycloaddition the dioxastannacyclohexene 5. All compounds were submitted to detailed 1H and 13C NMR study. The structures of 2, 3, and 5 were determined by X-ray crystallography.