91999-52-9Relevant academic research and scientific papers
Synthesis and Rearrangement of Alkylaryl- and Aryl-substituted Dihydrosemibullvalenes by Thermolysis of 7,8-Fused Cyclo-octa-1,3,5-triene Derivatives
Greenfield, Simon,Mackenzie, Kenneth
, p. 1651 - 1666 (2007/10/02)
The thermal cycloaddition of a cyclobuteno-dienophile (1) with cyclopentadienones has been systematically investigated; the stereoisomeric adducts give convenient access by decarbonylation to a variety of tetra-aryl, methyltriphenyl-, triphenyl-, tri-t-butyl-, and dimethyldiphenyl-cyclo-octa-1,3,5-triene derivatives as the products of electrocyclic ring-opening of the valence-tautomeric primary products of cheletropic bridge-extrusion, viz. bicyclooctadienes.These compounds provide useful models for investigation of equilibria between the electrocyclic valence tautomers, the scope and mechanism for thermal cross-cyclisations in, for example, unsymmetrically substituted cyclooctatrienes, and the thermal vinyl-cyclopropane (1,3-allylic shift) isomerisation and/or H-atom transfer disproportionation of the resulting arylated and alkylaryldihydrosemibullvalenes.The results best accord with diradical pathways for cyclo-octatriene-dihydrosemibullvalene conversions and subsequent rearrangements.Usefull 13C and 1H n.m.r. structure correlations and new examples of cyclopentadienones are also reported.
THERMAL REARRANGEMENT OF ALKYLARYLDIHYDROSEMIBULLVALENE DERIVATIVES: HYDROGEN ATOM TRANSFER PROCESSES
Greenfield, S.,Mackenzie, K.
, p. 2259 - 2262 (2007/10/02)
Alkylaryldihydrosemibullvalene derivatives, besides exhibiting vinylcyclopropane type rearrangements typical of tetraarylated analogues, also undergo H atom transfer from methyl groups, most easily understood in terms of biradical intermediates rsulting from alternative modes of cyclopropane ring scission.
