- Organic Photochemistry with 6.7-eV Photons: The Photochemistry of Bicyclohept-2-ene (2-Norcarene)
-
The photochemistry of bicyclohept-2-ene (2-norcarene) upon direct and triplet-sensitized photolysis has been investigated.The results differ significantly from those of previous studies on related systems.Direct photolysis with monochromatic radiation in the region 185-230 nm leads to a variety of products, of which cis-1,3,6-heptadiene, the major product, is shown by deuterium labeling studies to result from formal electrocyclic ring opening in a manner analogous to the 1,3-cyclohexadiene/1,3,5-hexatriene interconversion.The evidence suggests that this process may occur via a concerted mechanism in the singlet state.The other products arise from activation of the two cyclopropane bonds that are in conjugation with the olefinic group.The product distribution is independent of both solvent and excitation wavelength and is unchanged by the addition of naphthalene.Toluene-sensitized photolysis results in the formation of cis-1,3,6-heptatriene and bicyclohept-2-ene, which can be rationalized as resulting from decay of a common biradical intermediate.
- Leigh, William J.,Srinivasan, R.
-
p. 514 - 519
(2007/10/02)
-
- Methyltriphenoxyphosphonium Iodide (MTPI); Induced Dehydration and Dehydrohalogenation in Aprotic Solvents
-
Methyltriphenoxyphosphonium iodide (MTPI) is an effective dehydration and dehydrohalogenation reagent under mild conditions when 1,3-dimethylimidazolidin-2-one is used as an aprotic solvent in place of the more normally used hexamethylphosphoric triamide (HMPT).Since previosly suggested mechanisms had proposed alcohol-HMPT interaction as an important mechanistic step, this result coupled with comparative product geometric isomer distributions and the conjugated: non-conjugated triene product ratios leads to the conclusion that MTPI-alcohol interaction with displacement of phenoxide is the primary step in the reaction.In dimethyl sulphoxide (DMSO) alcohol dehydratation is hindered by DMSO-MTPI interaction yielding dimethyl sulphide.
- Spangler, Charles W.,Kjell, Douglas P.,Wellander, Lori L.,Kinsella, Mary A.
-
p. 2287 - 2289
(2007/10/02)
-