PUB - Publikationen an der Universität Bielefeld

Three‐ and five‐membered rings that bear the (Si‐C‐S) and (Si‐C‐C‐C‐S) unit have been synthesized by the reactions of LSiCl (1; L=PhC(NtBu)2) and L′Si (2; L′=CH{(CCH2)(CMe)(2,6‐iPr2C6H3N)2}) with the thioketone 4,4′‐bis(dimethylamino)thiobenzophenone. Treatment of 4,4′‐bis(dimethylamino)thiobenzophenone with LSiCl at room temperature furnished the [1+2]‐cycloaddition product silathiacyclopropane 3. However, reaction of 4,4′‐bis(dimethylamino)thiobenzophenone with L′Si at low temperature afforded a [1+4]‐cycloaddition to yield the five‐membered ring product 4. Compounds 3 and 4 were characterized by NMR spectroscopy, EIMS, and elemental analysis. The molecular structures of 3 and 4 were unambiguously established by single‐crystal X‐ray structural analysis. The room‐temperature reaction of 4,4′‐bis(dimethylamino)thiobenzophenone with L′Si resulted in products 4 and 5, in which 4 is the dearomatized product and 5 is formed under the 1,3‐migration of a hydrogen atom from the aromatic phenyl ring to the carbon atom of the CS unit. Furthermore, the optimized structures of probable products were investigated by using DFT calculations.