3642-21-5Relevant academic research and scientific papers
Practical synthesis and Diels-Alder chemistry of [4]dendralene
Payne, Alan D.,Willis, Anthony C.,Sherburn, Michael S.
, p. 12188 - 12189 (2005)
Spectacular new atom efficient domino cycloaddition sequences involving [4]dendralene, the simplest cross-conjugated tetraene, are reported. Up to eight stereocenters, three new rings, and six C-C bonds are generated in one synthetic operation. The site s
Molecular Structure of 3,4-Dimethylenehexa-1,5-diene ([4]Dendralene), C8H10, in the Gas Phase As Determined by Electron Diffraction and ab Initio Calculations
Brain, Paul T.,Smart, Bruce A.,Robertson, Heather E.,Davis, Martin J.,Rankin, David W. H.,Henry, William J.,Gosney, Ian
, p. 2767 - 2773 (1997)
The molecular structure of 3,4-dimethylenehexa-1,5-diene ([4]dendralene), C8H10, has been determined in the gas phase. A single conformer with C2 symmetry, having two almost planar, anti butadiene groups orientated with a dihedral angle C(2)C(3)C(4)C(5) of 71.7(19) °, is detected by electron diffraction employing flexible restraints derived from ab initio computations. Other experimental structural parameters (rα/pm, ∠α/°) are: C(1)=C(2) 133.4(1), C(3)=C(7) (not in main chain) 134.0(1), C(2)-C(3) 147.4(2), C(3)-C(4) 149.6(3), C(1)C(2)C(3) 124.4(3), C(2)C(3)C(4) 119.2(5), C(4)C(3)C(7) 117.6(7), and C(7)C(3)C(2)C(1) -174.8(28). Ab initio computations at the MP2/6-311G* level predict that the vapor consists of ca. 90percent of the conformer found experimentally, the other 10percent comprising four other conformers.
First synthesis of the dendralene family of fundamental hydrocarbons
Fielder, Simon,Rowan, Daryl D.,Sherburn, Michael S.
, p. 4331 - 4333 (2007/10/03)
A neglected group of highly unsaturated hydrocarbons was how the dendralenes were described 16 years ago in a review in Angewandte Chemie. These compounds are neglected no more ! The hitherto unknown [5]-, [6]- (see scheme), and [8]dendralenes are synthesized by thermolysis of masked sulfolene derivatives which, in turn, are prepared by Stille coupling. The same approach offers an improved route to pure samples of [3]- and [4]dendralene, the full spectroscopic details of which are reported for the first time.
6,7-Dimethylene-3-thiabicycloheptane-3,3-dioxide, a Masked Form of Dendralene and Conjunctive Reagent for Tandem Annelations
Buchan, Caroline M.,Cadogan, J. I. G.,Gosney, Ian,Henry, William J.
, p. 1785 - 1786 (2007/10/02)
Previous limitations of highly reactive dendralene as a tandem annelating reagent in Diels-Alder reactions are overcome by use of its masked form, 6,7-dimethylene-3-thiabicycloheptane-3,3-dioxide (2), and subs
The Energy-Well of Diradicals, II. The 2,3-Dimethylene-1,4-cyclohexadiyl
Roth, Wolfgang R.,Scholz, Bernhard P.
, p. 1197 - 1208 (2007/10/02)
The trapping of the 2,3-dimethylene-1,4-cyclohexadiyl (2), generated by the thermolysis of 7, with 1,3-butadiene as well as with oxygen in the gas phase is described.These reactions compete with the intramolecular stabilisation of the diradical, yielding 3 and 4.From the temperature dependence of the competing processes the difference in the activation energies of these reactions is derived.On the assumption, that the trapping reaction with oxygen does not have any significant energy barrier, the energy-well of the diradical 2 is calculated to be 16 kcal/mol.
Thermolysis of 1,2,6,7-Octatetraene
Roth, Wolfgang R.,Scholz, Bernhard P.,Breuckmann, Rolf,Jelich, Klaus,Lennartz, Hans-Werner
, p. 1934 - 1946 (2007/10/02)
The energy profile for the rearrangement of 1 to 3 and 4 and their interconversion by way of 5 is established making use of kinetic methods and by the determination of the heat of hydrogenation of the individual products.For the Cope rearrangement 1 -> 4 the competition of concerted and non concerted reaction paths is demonstrated by trapping experiments.
Isolation and Energy Well of the 2,3-Dimethylene-1,4-cyclohexadiyl Diradical
Roth, Wolfgang R.,Biermann, Manfred,Erker, Gerhard,Jelich, Klaus,Gerhartz, Wolfgang,Goerner, Helmut
, p. 586 - 597 (2007/10/02)
Irradiation of both 5,6-dimethylene-2,3-diazabicyclooct-2-ene (1) and 2,3-dimethylenebicyclooctan-7-one (2) matrix isolated in argon yields the 2,3-dimethylene-1,4-cyclohexadiyl diradical (8), which was characterized by its UV and IR spectra.From the decomposition rate of 1, the dimerisation rate of 8, determined by flash photolysis of 1, and the product ratio of the monomeric and dimeric products obtained from 8, the energy well of 8 has been determined to be 23.8 kcal mol-1.
