Ajugatansins, neo-clerodane diterpenes from Ajuga reptans.

New neo-clerodane diterpenes have been isolated from Ajuga reptans, and named ajugatansins, along with the previously reported ajugavensin A and ajugareptansone A. The structures of all the compounds were elucidated by spectroscopic means and comparison with closely related compounds reported in the literature. The new 6 alpha,19-diacetoxy-4 alpha,18-epoxy-1 beta-hydroxy-3 beta-(2-methyl-butanoyloxy)-neo-clerod-13-en-15,16-olide (ajugatansin A1) and 6 alpha,19-diacetoxy-4 alpha,18-epoxy-3 beta-hydroxy-12S-(2-methylbutanoyloxy)-neo-clerod-13-en-15,16-olide (ajugatansin B1) are structurally related to ajugarin I and (11S,13R,16S)-6 alpha, 19-diacetoxy-4 alpha,18:11,16:15,16-triepoxy-3 beta-(2-methylbutanoyloxy)-1 beta-[(E)-2-methyl-2-butenoyloxy]-neo-clerodan-2 beta-ol (ajugatansin D1) to dihydroclerodin.