Synthesis of the all-cis-trimethyldecalin fragment of unusual terpenes by radical-mediated protonolysis of an alkylboron derivative

The synthesis of an enantiopure building-block with a contiguous all-cis-trimethyldecalin motif embedded in unusual terpenes is described. Starting from the Wieland–Miescher ketone, the key step is a one-pot hydroboration of an exocyclic methylene double bond promoted by disiamylborane and radical-mediated protonolysis of the corresponding alkylborane using 4-tert-butylcatechol.