79999-68-1Relevant academic research and scientific papers
THE ACTIVITY SCALE OF DIPOLAROPHILES VERSUS THIOBENZOPHENONE S-METHYLIDE
Huisgen, Rolf,Xingya, Li
, p. 4185 - 4188 (1983)
Competition experiments of pairs of dipolarophiles for thiobenzophenone (2) furnish relative rate constants which reveal an unusually high selectivity of the nucleophilic 1,3-dipole, in accordance with Sustmann's PMO concept.
'Thiobenzophenone S-Methylide" (=(Diphenylmethylidenesulfonio)methanide), and C,C Multiple Bonds: Cycloadditions and Dipolarophilic Reactivities
Huisgen, Rolf,Li, Xingya,Giera, Henry,Langhals, Elke
, p. 981 - 999 (2007/10/03)
Thiobenzophenone and diazomethane afford thiadiazoline 1 at -78 deg C. By elimination of N2 from 1 at -45 deg C (t1/2 ca. 1 h), (diphenylmethylidenesulfonio)methanide (2), which cannot be isolated but is interceptible by dipolarophiles, is set free. The nucleophilic 1,3-dipole 2 undergoes cycloadditions with electrophilic C,C multiple bonds; the structures of 16 cycloadducts were elucidated. One-step and two-step cycloaddition pathways are discussed in the light of the steric course observed for (E)/(Z)-isomeric ethylene derivatives. Competition experimetns with pairs of dipolarophiles at -45 deg C and HPLC analysis of the adducts provided relative rate constants of 26 dipolarophiles, involving 2 CC, 13 C=C, 9 C=S, and 2 N=N bonds. In accordance with Sustmann's reactivity model of concerted cycloadditions, 2 shows the highest selectivity of all known 1,3-dipoles, i. e., the largest spread of rate constants (krel = 1 for methyl propiolate and 33 x 106 for TCNE). As a consequence of low LU energies, thiones are very active dipolarophiles, and fluorene-9-thione (krel = 79 x 106) stands at the top.
NEW REACTIONS OF THIOBENZOPHENONE S-METHYLIDE
Xingya, Li,Huisgen, Rolf
, p. 4181 - 4184 (2007/10/02)
2,2-Diphenyl-1,3,4-thiadiazoline, prepared from thiobenzophenone and diazomethane at -78 deg C, extrudes N2 at -45 deg C and allows to study in situ 1,3-cycloadditions of thiobenzophenone S-methylide (3) with electrophilic C=S, C=C, CC, and N=N bonds.
