Photolyses and pyrolyses of triterpenoid nitrites

Abstract

Derivatives of 19β,28-epoxy-18α-oleanane and lupane with nitrosyloxy group in positions 1α, 2β, 3α, 3β and 28 (II, V, VIII, X and XXVII, respectively) were subjected to photolysis in solution and in the crystalline state, as well as to pyrolysis. In most cases the products identified were alcohols, ketones, olefins and seco derivatives. Photolysis of 2β-nitrile V in benzene afforded the known 24- and 25-oximino derivatives XV and XVII, photolysis of 1α-nitrite II in the crystalline state led to the little stable form XIX of N-hydroxylactam XXI which in solution was easily converted into the derivative of O-acyl-N-alkylhydroxylamine XXII. Photolysis of crystalline 3β,28-lupanediyl 3-acetate, 28-nitrite XXVII gave 28-norolefins XXX and XXXI and 13β,28-epoxy derivative XXXII.