CYCLOADDITIONS .23. MERCURY-SENSITIZED GAS PHASE PHOTODECARBONYLATION OF 3,3-DIDEUTERIO- AND EXO- AND ENDO-3-DEUTERIONORCAMPHOR

The mercury-sensitized gas phase photodecarbonylation of 3,3-dideuterionorcamphor gave 1,1- and 3,3-dideuteriohexa-1,5-diene in a 90:10 ratio; (3,3-dideuterioallyl)- and (1,1-dideuterioallyl)cyclopropane and allyldideuteriocyclopropane in a 45:45:10 ratio; and 5,5-dideuterio- and 2,2-dideuteriobicyclo[2.1.1]hexane in a 93:7 ratio. Photodecarbonylation of exo- and endo-3-deuterionorcamphor gave quantitatively analogous data; equal portions of exo- and endo-5-deuteriobicyclo [2.1.1] hexane and the same ratio of cis- and trans-1-deuteriohexa-1,5-diene were formed from either labeled ketone. These results are interpreted in terms of the known kinetics of the decarbonylation, diradical intermediates as precursors of the hydrocarbon products, and a Cope rearrangement that competes with collisional deactivation of the 1,5-hexadiene produced through the decarbonylation process. © 1969, American Chemical Society. All rights reserved.