77300-33-5Relevant 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.
THE THERMAL REARRANGEMENT OF TETRA-ARYLATED DIHYDROSEMIBULLVALENE DERIVATIVES, AND (1)H/(13)C NMR-STRUCTURE CORRELATIONS
Greenfield, S.,Mackenzie, K.
, p. 2255 - 2258 (2007/10/02)
A systematic study of the thermal cyclisation of isomeric di-p-anisyl-diphenylcyclooctatriene derivatives, and of the facile isomerisation of the resulting dihydrosemibullvalenes, with 1H/13C nmr-structure correlations, supports earlier proposals for rearrangement mechanism.
PERICYCLIC TRANSFORMATIONS OF TETRACYCLO2,903,8>TRIDECA-4,6,11-TRIENES, AND FORMATION OF DIHYDROSEMIBULLVALENES BY THERMAL INTRAMOLECULAR?4a+?2a>CYCLOADDITION IN SUBSTITUTED CYCLOOCTATRIENES
Lay, W. P.,Mackenzie, K.,Miller, A. S.,Williams-Smith, D. L.
, p. 3021 - 3031 (2007/10/02)
Cyclopentadienones react with certain cyclobutene dienophiles to give the anticipated carbonyl bridge adducts; these, on relatively mild thermolysis, yield dihydrosemibullvalene derivatives by a novel sequence including cheletropic loss of carbon monoxide, electrocyclic ring opening of immediate substituted bicyclooctadienes, and intramolecular ?4a + ?2a>cycloaddition of the derived cyclooctatrienes.Other pericyclic reactions of compounds related to those of the title compounds are also discussed.
NOVEL REARRANGEMENT AND CRYSTAL STRUCTURE OF TETRAARYLATED DIHYDROSEMIBULLVALENE DERIVATIVES
Taylor, G. E.,Mackenzie, K.,Fray, G. I.
, p. 4935 - 4938 (2007/10/02)
The structure of a dihydrosemibullvalene, 3, previously deduced from nmr and mass spectrometry and from chemical transformation of an analogue - is confirmed by X-ray analysis.The thermal rearrangement of other analogous arylated dihydrosemibullvalenes is disclosed.
