An improved general synthetic approach to cis-clerodane diterpenoids. A more efficient total synthesis of (±)-6β-acetoxy-2-oxokolavenool

The previously developed general synthetic approach to cis-clerodane diterpenoids has been greatly improved using 4-(2-benzyloxy)ethyl-2-cyano-4-methyl-2,5-cyclohexadien-1-one (4) as the starting dienophile. This approach allows the direct incorporation of an angular methyl group via reductive alkylation of the α-cyano ketone system. The viability of this approach to cis-clerodanes has been demonstrated in the alternative total synthesis of (±)-6β-acetoxy-2-oxokolavenool (1).