55755-08-3Relevant academic research and scientific papers
Large Intrinsic Nuclear Magnetic Resonance Isotope Shifts Associated with Bending Motion along the Bridging Coordinate in Carbocations
Forsyth, David A.,Botkin, James H.,Puckace, James S.,Servis, Kenneth L.,Domenick, Robert L.
, p. 7270 - 7276 (1987)
Deuterium isotope effects on the 13C NMR chemical shifts have been determined for the 2-methyl-2-bicyclooctyl and 2-methyl-2-bicycloheptyl cations.These tertiary carbocations have isotope shifts that are larger than 1 ppm per deuterium, which is an order of magnitude larger than ordinary intrinsic shifts found in nonionic model compounds and in other carbocations.For deuteriation at C3 methylene or methyl group, the same pattern occurs in both cations: isotope shifts that are large and upfield at C2, downfield at C1, and upfield at the remaining carbon directly bonded to C2.The similarity in the pattern of the isotope shifts suggests that the force field and shielding influences in both ions are similar.The specific results are interpreted as indicating the presence of a shallow potential surface for the bending motion along the direction associated with ?-bridging.Since the existence of the shallow potential does not depend on the actual extent of bridging, the magnitude of the isotope effect is not proportional to the extent of bridging.
Adamantane Chemistry. Part 3. Abnormal Hypoiodite Reactions of 2-Substituted Adamantan-2-ols; Synthetic Routes to 4-Oxahomo- and 2-Oxa-adamantanes, and 7-Substituted-bicyclononan-3-ols
Black, Robin M.,Gill, G. Bryon
, p. 410 - 418 (2007/10/02)
Reaction of 2-methyladamantan-2-ol (1a) with lead tetra-acetate and iodine in boiling benzene did not yield the expected radical fragmentation product (3a), but rather a yellow, crystalline di-iodo-ether which was previously assigned structure (4) on the basis of chemical degradative evidence and on an apparent m/e 418 molecular ion (electron impact).Structure (4) is not supported by the spectroscopic data, and 13C n.m.r. studies on an isotopically enriched sample of the di-iodo-ether indicate the structure to be (5b).Re-investigation of the mass spectrum has revealed that the (fairly intense) molecular ion has m/e 416; previous assignment of the molecular ion to the m/e 418 peak (i.e.M+2) arose largely through the absence at that time of mass-marking facilities and the large interval between M.+ and the highest mass fragment ion.Similar hypoiodite reaction of 2-ethyl- (1b) and of 2-phenyl-adamantan-2-ol (1c) gave, respectively, the products (5a) and (7b), the latter arising from the hydrolysis during isolation of the iodo-ether (6c).Investigation of the chemistry of (5b) and (7b) has revealed useful preparative routes to substituted 4-oxahomo- and 2-oxa-adamantanes as well as 7-substituted-bicyclononan-3-ols.Several unusual reactions have been discovered, and reaction mechanisms are suggested.
