[The structure identification of pyridinemono terpene isocantleyine]

Siphonostegia chinensis Benth. as a traditional Chinese medicine "liujinu" has been used for centuries in China, but up to date little has been reported about its chemistry. Now, four compounds have been isolated from the aerial parts of this genus. On the basis of spectroscopic analysis (UV, IR, MS, 1HNMR, 13CNMR and 2D-NMR) and chemical evidences, compound I was shown to be a new pyridinemonoterpene alkaloid which is a stereoisomer of the known compound cantleyine, and named isocantleyine. Its structure was determined as 5H-2-pyridine-4-carboxylic acid, 6,7-dihydro-6-hydroxy-7-methyl-methyl ester. Compound III was identified as the known compound loliolide. The other two (II and IV) are still under investigation. This paper deals mainly with the structure identification of compound I.