Norbomen retro-Diels-Alder reaction

Dienyl esters (442 = Ph), available via a retro-Diels-Alder reaction of norbomene (441 = Ph),... 

Subsequent work on the parent molecule revealed less inversion at Cl. In one study at 276°C, 76 4% was observed, and in the other at 312°C, 89% inversion was observed. Both studies examined the pyrolysis of xo, xo-6,7-dideuteriobi-cyclo[3.2.0]hept-2-ene, and found that starting material did not epimerize significantly at Cl under the reaction conditions (subsequently a small amount was measured ), and that the norbomene produced rapidly underwent a retro Diels-Alder reaction so that at most 2% of it was present at any time (Scheme 8.46). 

Laser-induced and thermal retro-Diels-Alder reactions of norbomene have been investigated with B3LP, CASSCF, and CASPT2 methods. Kinetic studies show that the cycloaddition of l-amino-3-siloxy-1,3-dienes proceeds via a concerted 4-1-2-mechanism, with a relatively low activation barrier. The Diels-Alder reaction between hexachlorocyclopentadiene and ethyl vinyl ether has been shown to be stereo-speciflc since the variation in cis versus trans deuterium content in the natural abundance ethyl vinyl ether is retained in the cycloadduct product. ... 

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