A NEW APPROACH TO THE SKELETONS OF BOTH THE APHIDICOLIN AND STEMODIN DITERPENOIDS

We describe a concise synthesis of 4,4,10,16 tetra-desmethyl-1,2,3,4-t etra-dehydro-16 alpha-hydroxystemodan-13-one which has the skeleton of the diterpene stemodin using a trimethylsilyl ketyl radical / nitrile cyclisation of 1,1-bis-cyanoethyl-2-tetralone as the key step. This c ompound could be transformed to 4,4,10,16 tetra-desmethyl-1,2,3,4-tetr a dehydro-16 alpha-hydroxyaphidicolane, which has the skeleton of aphi dicolin via hydrogenation of the alkene derived from aprotic Bamford S tevens elimination of an arylsulphonylhdydrazone derivative.