Studies in the Bicyclo[2.2.1]heptane Series. V. Reactions of Bicyclo[2.2.1]heptadiene¹

Nortricyclyl−Norbornenyl Cation System Accessed by Carbene Fragmentation

“…These ethers were prepared as a mixture. 35 To a solution of 5.2 g of 96% sulfuric acid in 50 g of absolute methanol (10% sulfuric acid solution in methanol) was added 10 g (0.10 mol) of norbornadiene. The mixture was heated under slow reflux for 2 h. The mixture was poured into 150 mL of water and extracted with 3 × 100 mL of pentane.…”

Tuning Molecular Solar Thermal Properties by Modification of a Promising Norbornadiene Photoswitch

“…As envisaged for compound 13 , the major product, an acetyl group was indeed introduced to the 7‐position, along with addition of hydrogen chloride across the olefin at C5–C6. This type of addition pattern is synonymous with a Wagner–Meerwein rearrangement, which is also the same type of reaction pathway found for the bromination of NBD4 and benzonorbornene . Minor product 14 was identified as a nortricyclene structure.…”

“…The regiochemistry of this undesired by‐product was confirmed using an assortment of NMR experiments (see ESI). Halogenated nortricyclenes of this type have been observed by subjecting NBD4 to either hydrochloric or hydrobromic acids; as it is possible that hydrochloric acid was present in this reaction mixture, this would explain the production of 14 . To conclude, these reaction conditions allowed for a C–C bond forming reaction at C7 and importantly, it was conceivable that an elimination of hydrochloric acid could restore the double bond and thus photochromism to the NBD derivative.…”

“…It was thought that the driving force for this epimerisation under these thermodynamic conditions was the alleviation of steric interaction between the acetyl group and the bromine atom. Treatment of 17 with potassium tert ‐butoxide, using a literature procedure suitable for the formation of benzonorbornenes, gave elimination of hydrogen bromide affording NBD18 in excellent yield. The bulky ketal substituent could be dismantled under aqueous acidic conditions giving the 7‐acetyl‐substituted NBD19 , with the regiochemistry preserved in this step.…”

The Peroxidation of Bicyclo [2.2.1]heptadiene

“…This work is incomplete, but is presented at this time in view of work in another laboratory. 7 Diisopropyl ether was used first, but the chlorosulfinate from l-hexyn-3-ol decomposed only slowly at the boiling point of this solvent (68°). In bis-(2-ethoxyethyl) ether (diethyl Carbitol) at 100-120°this chlorosulfinate gave about the same pro-(8) S. H. Sharman, F. F. Caserío, Jr., R. F. Nystrom, J. C. Leak and W. G. Young, This Journal, 80, 5965 (1958).…”