934362-16-0Relevant academic research and scientific papers
Dichotomy of 1,3-dipolar cycloreversions in a tetrasubstituted 2,5-dihydro-1,3,4-thiadiazole
Langhals, Elke,Huisgen, Rolf
, p. 443 - 448 (2007/10/03)
The cycloaddition of diphenyldiazomethane (8) to 16 thiohetones at 40°C which furnishes tetrasubstituted 2,5-dihydro-1,3,4-thiadiazoles, is followed by rapid N2 loss (see the preceding paper), with one exception: For the dihydrothiadiazole 10,
1,3-Dipolar cycloadditions of diphenyldiazomethane to thioketones: Rate measurements disclose thiones to be superdipolarophiles
Huisgen, Rolf,Langhals, Elke
, p. 433 - 442 (2007/10/03)
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.
THIONES AS SUPERDIPOLAROPHILES
Huisgen, Rolf,Langhals, Elke
, p. 5369 - 5372 (2007/10/02)
According to kinetic measurements,the 1,3-cycloadditions of diphenyl-diazomethane to thioketones are much faster than those to α,β-unsaturated carbonyl compounds and nitriles previously regarded as record dipolarophiles.The primary cycloadducts are tetrasubstituted 1,3,4-thiadiazolines which extrude N2 and furnish thiiranes via thiocarbonyl ylides.
