Collect. Czech. Chem. Commun. 1986, 51, 2029-2033

Reduction of triterpenoid ketones by chloroiridic acid and trimethyl phosphite

Jiří Protiva, Eva Klinotová, Jiří Klinot, Miroslav Kušiak and Alois Vystrčil

Department of Organic Chemistry, Charles University, Albertov 2030, 128 40 Prague 2


Selective reduction of keto groups on triterpenoid pentacyclic skeleton by chloroiridic acid and trimethyl phosphite (Henbest method) was studied. The 2-oxo group is stereospecifically reduced to give axial 2β-hydroxy group whereas oxo groups in positions 1,3,11,12,16,20,21,22, and 28 do not react. An analogous reduction was observed with a 2-oxo steroid.