En la hidroxilación alílico del ácido ent kaurénico con SeO2

Abstract

Allylic hydroxylation of ent-kaur-16-en-19-oic acid (1a) with SeO2 was tried using either dioxaneor dichloromethaneas solvents as well as different reagent and reaction time conditions at roomtemperature. Oxidation of 1a indioxane with H2O2 decreased reaction time but led to the formation of many by-products on addition to ent-15Dhydroxy-kaur-16-en-19-oicacid (2a), which was the main product. Using dichloromethane as solvent without addition of H2O2 made the reaction slower and yielded mainly 2a (70% at 24 h, 53% at 48 h) and ent-17-oxo-kaur-15,16-en-19-oic acid (3a,18% at 24 h, 43% at 48 h). The course of the reaction was followed by GC-MS, aftermethylation of the reaction mixtures.