101763-97-7Relevant articles and documents
1,3-Dipolar cycloadditions of diphenyldiazomethane to thioketones: Rate measurements disclose thiones to be superdipolarophiles
Huisgen, Rolf,Langhals, Elke
, p. 433 - 442 (2006)
1,3-Dipolar cycloadditions of diphenyldiazomethane to thioketones afford 2,5-dihydro-1,3,4-thiadiazoles 8, which rapidly lose N2. The liberated thiocarbonyl ylides 10 furnish thiiranes 9 by electrocyclic ring closure. The rate constants, measured by spectrophotometry (DMF, 40°C) for 16 cycloaliphatic and aromatic thioketones and one cyclic trithiocarbonate, stretch over five powers of 10 with fluorene-9-thione at the top and 2,2,5,5-tetramethylcyclopentanethione at the bottom. Electron-releasing substituents decrease the cycloaddition rate of thiobenzophenone; thus, the ambiphilic diphenyldiazomethane reacts as nucleophilic partner with the electrophilic thioketone. The influence of substituents and ring size on the reactivity of cycloalkanethiones, which are sterically hindered by two gem-dimethyl groups, will be discussed. Compared with electron-deficient C=C and C≡C bonds, thiones are superdipolarophiles.
