Collect. Czech. Chem. Commun. 1988, 53, 118-131

Photolysis of 19β,28-epoxy-18α-oleanan-2β-ol nitrites: Functionalization of 10β- and 8β-methyl groups

Jan Sejbal, Jiří Klinot and Alois Vystrčil

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


On photolysis, 19β,28-epoxy-18α-oleanan-2β-ol nitrite (I) undergoes functionalization of the 10β-methyl group (formation of oxime II) as well as of the rather distant 8β-methyl group (leading to oxime III). No products of attack at the 4β-methyl group have been found. The 2β-nitrolyloxy-3β-acetoxy derivative XX reacts similarly whereas its 2β-nitrosyloxy-3α-acetoxy isomer XIII is photolyzed to give diol XI. Oximes II and III were converted into two series of nitriles (a and b) with various functional groups on the ring A. Structure of all compounds was derived from their spectral data. Double radical transfer has been proposed for functionalization of the 8β-methyl group (position 26).