116504-60-0Relevant articles and documents
Improved Synthesis of 2,6-Dicyano-1,5-dimethylsemibullvalene from 1,5-Dimethylbicyclooctane-3,7-dione
Quast, Helmut,Mayer, Andreas
, p. 1155 - 1164 (2007/10/02)
The 3,7-diketone 6 reacts with thiophenols in the presence of titanium tetrachloride/triethylamine affording equal amounts of the vinyl sulfides C2/Cs-13 in 87-93percent yield.Equilibration of the 1:1 mixture of C2/Cs-13 is catalyzed by trifluoroacetic acid and produces a 3:1 ratio of C2- and Cs-13.Sodium perborate tetrahydrate in acetic acid oxidizes the vinyl sulfides C2/Cs-13 to the vinyl sulfones C2/Cs-14 in almost quantitative yield.Potassium cyanide supported on aluminium oxide in boiling 2-methyl-2-butanol converts the latter into a mixture of α,β-unsaturated dinitriles 8, 17, Cs-18, 19, 20 which are separated through chromatography.The major product 8 (yield 45-55percent) exchanges the allylic protons on treatment with sodium methoxide in methan-ol yielding -8.Both dinitriles 8 and -8 are brominated by N-bromosuccinimide in dichloromethane to afford the exo,exo-4,8-dibromodinitriles 22 and -22, respectively, which are debrominated by means of the zinc/copper reagent.Thus, a 78-85percent yield of the 2,6-dicyanosemibullvalenes 1 and -1, respectively, is achieved on a 2-g scale.
