Allylic oxidation of phlomisoic acid and its methyl ester by selenium dioxide occurred stereoselectively to form 7D-hydroxy derivatives of labdanoids, which were oxidized by active manganese dioxide to 7-ketofuranolabdanoids. Oximation of the last by hydroxylamine hydrochloride in MeOH in the presence of NaOAc gave pure (E)-ketooximes. Beckmann rearrangement of 7-ketooximes of phlomisoic acid and its methyl ester occurred with formation of the corresponding octahydro-1H-benzoazepines.Keywords: phlomisoic acid, synthesis, 7R-hydroxy-15,16-epoxy-8(9),13(16),14-labdatrien-18-oic acid, 7-ketolabdanoids, oximes, 5-furan-3-ylethylbenzoazepines, XSA.Furan-containing labdanoids functionalized in ring B were isolated from extracts of plants that exhibit sedative and uterotonic properties and are used in folk medicine for cardiovascular disorders [2]. 7-Keto-and 7-hydroxyfurolabdanoids showed antibacterial [3], antifeedant [4], and cytotoxic activity [5]. The isolation of 8,9-secofuranolabdanoids that exhibited cytotoxicity against human tumor cells was reported [6]. Promising inhibitors of N-O synthase were recently found among labdanoids modified in ring B [7]. Therefore, it seemed interesting to synthesize modified labdanoids. Currently known approaches are most often based on transformations of available natural metabolites [8,9]. We proposed earlier methods for preparing the plant diterpenoid phlomisoic acid (1) and its ester 2 from lambertianic acid, an available metabolite of Pinus sibirica R. Major [10,11]. Herein results from a study of the transformations of furanolabdanoids 1 and 2 in ring B are reported.Allylic oxidation of 1 and 2 by SeO 2 in dioxane occurred stereoselectively to form 7D-hydroxy derivatives 3 and 4 (59 and 74% yields, respectively) (Scheme 1). This could be explained by attack of the reagent from the less hindered D-side.