Novel labdane diterpenes from the insecticidal plant Hyptis spicigera

Seven new labdane diterpenes with insecticidal properties were isolated fro m the aerial parts of Hyptis spicigera. Their structures were established o n the basis of spectral (MS, H-1 NMR, and C-13 NMR) and chemical evidences as:19-acetoxy-2 alpha,7 alpha,15-trihydroxylabda-8(17),(13Z)-diene(1); 15,1 9-diacetoxy-2 alpha,7 alpha-dihydroxylabda-8(17),(13Z)-diene (2); 7 alpha,1 5, 19-triacetoxy-2 alpha-hydroxylabda-8(17),(13Z)-diene (3); 19-acetoxy-2 a lpha,7 alpha-dihydroxylabda-8(17),(13Z)-dien-15-al (4); 19-acetoxy-2 alpha, 7 alpha-dihydroxylabda-8(17),(13Z)-dien-2-one (5); 19-acetoxy-2 alpha,7 alp ha-dihydroxylabda- 14,15-dinorlabd-8(17)-en-13-one (6); and 2 alpha,7 alpha ,15,19-tetrahydroxy-ent-labda-8(17),(13Z)-diene (7). Absolute configuration s were established by application of Mosher's method. Compound 2 significan tly inhibited larval growth of the European corn borer.