Abstract
A formal synthesis of valerenic acid is described. The systhesis began with 1,4-addition of enone 74 followed by iodination to provide α-iodo ketone 73. The key step involved a radical cyclization of α-iodo ketone 73 to construct the [6,5]-bicyclic skeleton. Treatment of 82 with NaI and DBU resulted in elimination of tosylate followed by reduction of enone 71 and subsequent silyl protection of alcohol 84 gave 86. Hydrogenation of 86 followed by desilylation afforded alcohol 85. Conversion of 85 into the known intermedium ketone 43 completed the formal synthesis.