Hydroboration by Diborane of Methyl Abietate

Hydroboration-oxidation of methyl abietate by diborane in THF occurred preferentially at the sterically unhindered β -side of the molecule without involving the ester. The known hydroboration-oxidation product methyl 7 β -hydroxy-13 α -isopropylpodocarp-8(14)-en-15 α -oate and previously unknown methyl 7 β -hydroxy-13-isopropyl-8 β -podocarp-13(14)-en-15 α -oate, 14 β -hydroxy-13 α -isopropylpodocarp-7(8)-en-15 α -oate, and 7 β ,14-dihydroxy-13 α -isopropyl-8 β -podocarpan-15 α -oate, i.e., products from monohydroboration-oxidation at the ∆ 7,8 - and ∆ 13,14 -bonds without their respective shifts and from dihydroboration, were obtained.