BRIDGED POLYCYCLIC COMPOUNDS .54. REARRANGEMENTS ATTENDING RADICAL-ANION REDUCTION OF DEHYDRONORBORNYL AND NORTRICYCLYL CHLORIDES

exo-Dehydronorbornyl chloride (7 CI), its endo epimer (9 CI) and nortricyclyl chloride (8 CI) were reduced by sodium biphenyl radical anion to mixtures of norbornene (7, Y = H) and nortricyclene (8, Y = H). At room temperature, all three chlorides gave identical mixtures containing about two-thirds nortricyclene. However, at - 58° the unsaturated chlorides gave mixtures substantially richer in norbornene (ca. one-third nortricyclene), and the tricyclic chloride gave mixtures richer in nortricyclene (ca. 87% 8, Y = H). Rapid carbonation of the reaction mixture from the exo chloride resulted in the formation of 3-nortricyclenecarboxylic acid (12) in very low yield. The results are rationalized in terms of an initial reduction to classical radicals and competition between rearrangement of these radicals to each other and capture by reduction to carbanions. © 1969, American Chemical Society. All rights reserved.