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Norbornanes . Part 21. Bridging strain in norbornyl and oxanorbornyl cations
Author(s) -
Flury Peter,
Grob Cyril A.,
Wang Guang Yi,
Lennartz HansWerner,
Roth Wolfgang R.
Publication year - 1988
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19880710512
Subject(s) - chemistry , 2 norbornyl cation , oxonium ion , ion , heptane , bicyclic molecule , strain (injury) , bridging (networking) , medicinal chemistry , ionization , stereochemistry , standard enthalpy of formation , computational chemistry , organic chemistry , medicine , computer network , computer science
Further evidence is presented that the 2‐norbornyl cation is stabilized primarily by C(2)–C(6) bridging, and that C(2)–C(7) bridging leads to prohibitive strain. Thus, a comparison of the heats of hydrogenation of nortricyclene 17 and bicyclo[3. 2. 0. 0. 2,7 ]heptane 18 indicates that the strain energy of the latter is ca. 21.5 kcal/mol higher that that of 17 . Furthermore, 6‐ exo ‐2‐oxabicyclo[2. 2. 1]heptyl sulfonates 8 ionize with strong O(2) participation to the bridged oxonium ion 12. In contrast, 2‐ endo ‐7‐oxabicyclo[2.2.1]heptyl sulfonates 11 ionize without O(7) participation to form the unbridged carbenium ion 15 .