Novel norcassane-type diterpene from the seed kernels of Caesalpinia crista

Three novel norcassane-type diterpenes were isolated from a CH2Cl2 extract of the seed kernels of Caesalpinia crista together with four known cassane-type diterpenes. All the new compounds represent unprecedented carbon framework. Norcaesalpinin A (1) and B (2) had 17-norcassane skeleton, while norcaesalpinin C (3) had 16-norcassane skeleton. Their structures were elucidated on the basis of spectral...