Novel labdane diterpenes from the insecticidal plant hyptis spicigera1

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