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. (C) 2014 Elsevier Ltd. All rights reserved.