Chemistry of silyl thioketones. Part 4. 2,4,6-Triaryl-2,4,6-tris(trimethylsilyl)-1,3,5-trithianes from silyl thioketones: crystal structure of 2,4,6-triphenyl-2,4,6-tris(trimethylsilyl)-1,3,5-trithiane and stereochemistry of desilylation with fluoride ion

Silyl thioketones are easily converted into the corresponding trimers (1,3,5-trithianes) under acidic conditions. Both the α-(cis,trans)- and the β-(cis,cis)-isomers were isolated. The β-diastereoisomers predominate over the α-form. The major isomer from the trimerisation of trimethylsilylphenyl thioketone, upon X-ray analysis, shows a chair-like conformation with the silyl groups all equatorial. Desilylation of the α- and β-trimers of the trimethylsilylphenyl thioketone with fluoride ion affords, stereospecifically, the two isomeric 2,4,6-triphenyl-1,3,5-trithianes.