6007-21-2Relevant academic research and scientific papers
1,3-Dithienium- and 1,3-Dithiolenium Salts, V. Determination of the Relative Reactivity of 1,3-Dithian-2-ylium Tetrafluoroborates by Intermolecular Hydride Ion Transfer
Stahl, Ingfried
, p. 4857 - 4868 (2007/10/02)
The 1,3-dithienium- and 1,3-dithiolenium tetrafluoroborates 4 (n=3, 2) react in good yields with the (trimethylsiloxy)alkenes 3 available from β-dicarbonyl compounds to give the 2-substituted 1,3-dicarbonyl compounds 5.Owing to the formation of the difluoroboron acid esters 8 as competition products 3 has to be employed in excess, however.Reaction of 4 (n=3) with 1,3,5-cycloheptatriene (10) leads to the 1,3-dithianes 11 and the more stable tropylium tetrafluoroborate (12).The determination of the corresponding rates of reduction allows in a simple manner the ascertainment of the relative reactivities of 4.Whereas the reactivities of the aryl-substituted representatives of 4 show a sufficient correlation corresponding to the Hammett relationship, the variations of the reactivities of the alkyl substituted salts 4 can be explained on the basis of hyperconjugative stabilization.
