- no.15, pp.169-176, 1971-10-01
The results of the synthetic studies on several steroidal alkaloids of salamander and frog venoms were presented. (1) Cycloneosamandione (VIII) and Cycloneosamandaridine (IX) Recently, the early proposed structure of cycloneosamandione (VI), which had been determined by G. Habermehl with the X-ray diffraction method, has been revised to be VIII on the basis of his own synthetic work. In order to reconfirm this structure, the compound VIII was synthesized by the sequre synthetic sequence. As a result, the physical data of the synthetic specimen were consistent with those of the natural product. Cycloneosamandaridine has been known as one of the minor constituents of the salamander alkaloids. Since this alkaloid has been recognized to have the identical skeleton with cycloneosamandione, the structure, we suppose, should be also revised to be IX from VII. Consequently, we have synthesized the compound IX via the same intermediate 16 as the synthesis of cycloneosamandione (VIII). The identification of our synthetic product with the natural one is now in progress. (2) Batrachotoxin (XI) The synthesis of batrachotoxin has been attempted. The treatment of the hemiacetal 27 with aminoethanol followed by reduction afforded a mixture of 18-hydroxyethylamino steroids (28a and 28b). Then the mixture was converted into the enone 36, which might serve as an useful intermediate for our purpose.