A new diterpene dimer from the bark of Chamaecyparis obtusa

This paper describes characterization of diterpenes of the bark of Japanese cypress, Chamaecyparis obtusa (S. and Z.) Endl, without the resinous stem canker to learn the difference between the cypress bark affected with the c anker. A diterpene dimer and two diterpenes, 6 alpha ,12-dihydroxyabieta-8, 11,13-trien-7-one and 6,12-dihydroxyabieta-5,8,11,13-tetraen-7-one, were fi rstly isolated from Japanese cypress. The dimer, 6-(abieta-6',8',11',13'-te traenyl-12'-oxy)-7-methoxyabieta-8,11,13-trien-12-ol, was a new compound. I t is a terpene indicative of C. obtusa not infected with the resinous stem canker. Five known diterpenes were also isolated.