Premium
The Reaction of Difluorocarbene with Bicyclo[2.2.2]octadiene
Author(s) -
Jefford Charles W.,
Delay Arlette,
Wallace Timothy W.,
Burger Ulrich
Publication year - 1976
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.19760590708
Subject(s) - difluorocarbene , chemistry , cyclopropane , norbornadiene , bicyclic molecule , adduct , intramolecular force , quadricyclane , moiety , thermal decomposition , bond cleavage , medicinal chemistry , cycloaddition , norbornene , photochemistry , stereochemistry , organic chemistry , polymerization , catalysis , ring (chemistry) , polymer
The addition of difluorocarbene to bicyclo[2.2.2]octa‐2,5‐diene gave the exo and endo 1:1 cyclopropane adducts. In contrast to norbornadiene, no homo ‐1,4 adduct was formed. The adducts were thermally stable under the conditions of their formation and separation (<170°). However, smooth equilibration was achieved on heating at 250° for 36 h. The same mixture resulted from either isomer. At 250° ΔΔ G = 1.83 kcal/mol; the endo isomer being the more stable. Heating to higher temperatures caused decomposition, rather than further reaction to the intramolecular [2+2]cyclization products. The kinetic and thermodynamic product compositions were essentially the same on extrapolating to the same temperature, viz. endo/exo = 19–22 at 25°. The mechanisms by which the cyclo‐addition and the stereomutation of the cis ‐fused cyclopropane moiety occur are discussed.