Neoclerodane diterpenoids from Scutellaria pontica

Seven novel neoclerodane diterpenoids, scupontins A-G, have been isolated from the Me2CO extract of the aerial parts of Scutellaria pontica (1-7), together with the known neoclerodanes scutalbin A and scutalpin M. Structures 1-7 were established by exhaustive NMR spectroscopic studies and chemical transformations. Scupontins A-D (1-4, respectively) and scupontins E (5) and F (6) possess unusual [(3'S,3''S)-3'-[(3''-acetoxybutyryl)oxy]butyryloxy and [(3'S,3''S,3'''S)-3'-[[3''-[(3'''-hydroxybutyryl)oxy]butyryl]oxy]butyryl]oxy substituents, respectively, attached to the C-19 position of the neoclerodane framework. In the case of the 6 alpha,7 beta-dibenzoate derivative 7 (scupontin G) its absolute configuration was established by the CD exciton chirality method.