Chiral Synthons from Carvone. Part 4. Radical Cyclization Strategies to Bridged Systems. Synthesis of Bicyclo(3.2.1)octan‐3‐ones from (S)‐ Carvone.

Radical cyclization of the bromo enones 2a-e, obtained by regiospecific bromoetherification reaction on theelectron-rich double bond of (S)-carvone (l), furnished regio- and stereospecifically bicyclo[3.2.1]octan-3-ones 3a-e and 4a-e. Analogously, radical cyclizations of the alcohols 6 and 7 gave bicyclo[3.2.1]octan-3-ols 8 and 9,and the bromo enones lla,b gave the bridgehead-substituted bicyclo[3.2.l]octan-3-ones 12a,b and 13a,b.