Generation, Trapping, and Dimerization of Pentacyclo[6.4.0.0^2,10.0^3,7.0^4,9]dodeca‐5,8,11‐triene: An Uncatalyzed Thermal [2+2+2+2] Cycloaddition

Abstract

Simultaneous formation of four CC bonds and three rings occurs in the unique uncatalyzed thermal [2+2+2+2] cycloaddition to give the tridecacyclotetracosane derivative 2, which takes place when the highly pyramidalized alkene 1 is generated in the absence of a trapping agent (see scheme).

Thermal Isomerization of 12‐Oxa‐1,9‐dimetylhexacyclo[7.2.1.02,4.02,8.03,7.06,8]dodec‐10‐ene: A Computational Mechanistic Investigation

“…The volatile material was condensed in a dry-ice/acetone-cooled trap. 2,4-Dimethyl-3-oxahexacyclo[5.5.0.0 1,10 .0 2,6 .0 4,10 .0 5,9 ]-dodec-11-ene (9a; 250 mg, 83%) was isolated as the sole product, besides some minor impurities (NMR) of unknown structure. 4 ) The structure of 9a was established by INADEQUATE NMR experiments.…”

“…An important structural difference between TS3 and TS4 are the distances C(2)ÀC(11) and C(8)ÀC (10). In TS3, there is no significant shortening of these nonbonding distances with respect to the starting molecule 5b, which shows a C(2)ÀC(11) interval of 2.408 (2.431); the corresponding ones of TS3 are 2.445 (2.473) and 2.391 (2.409).…”

“…Their hydrocarbon counterparts 7c and 8c, respectively, have been the subject of intensive investigation by Paquette and coworkers [7 ± 9]. Recently, Camps and co-workers found that a syn-sesquinorbornatriene derivative showed enhanced reactivity of the tetrasubstituted CC bond [10], which could also be expected for 7a/8a.…”

“…The recovery of the material amounted to 83%. After removal of some polymeric material, NMR analysis showed that no starting material was present and that 2,4-dimethyl-3-oxahexacyclo[5.5.0.0 1,10 .0 2,6 .0 4,10 .0 5,9 ]dodec-11-ene (9a) had been formed as the sole product.…”

Generation and Reactions of an Octacyclic Hindered Pyramidalized Alkene

“…Following our previous efforts, 5,18,20 in this study we report the generation of octacyclo[10.6.1.0 1,10 .0 3,7 .0 4,9 .0 8,19 .0 11,16 .0 13,17 ]nonadeca-5,8,14-triene (27), a hindered pyramidalized alkene, by using standard procedures from a diiodide precursor.…”