Alkaloids from dendrobatid poison frogs: Further pumiliotoxins and allopumiliotoxins and a reassignment of the keto function in pumiliotoxin 307F

The Synthesis of (+)-Allopumiliotoxin 323B′

“…Finally, the synthesis of ()-allopumiliotoxin 323B' (1) was completed with the removal of the BOM protecting group under reductive conditions using lithium di-tert-butylbiphenyl (LiDBB). [37,38] [39,40] and spectra provided by Overman. [41] Conclusion The synthesis of allopumiliotoxin was achieved in 20 steps from the b-hydroxyester (R)-13 with an overall yield of 1.7 %.…”

Alkaloids from Bufonid Toads (Melanophryniscus): Decahydroquinolines, Pumiliotoxins and Homopumiliotoxins, Indolizidines, Pyrrolizidines, and Quinolizidines

“…A Hewlett-Packard model 5890 gas chromatograph fitted with an HP-5 fused silica capillary column (25 mX0.32 mm) with the same program as used above for the ms analyses, interfaced with a Hewlett-Packard 5965A ir detector and a 59970IRD ChemStation, was used to generate the total response chromatogram and Ft-ir spectra of gc peaks. trans-223iF.-,, ,, "; m/z 223 (2), 222 (2), 180(100); ID; ir 2934 (100), 2873(47), 1455 (15), 1344 (7), 1131 (10) cm *; Ft-ir see Figure 1.…”

“…cis-249D.-,, ,, "; m/z 249 (2), 248 (3), 206 (100), 180 (15); ID; ir 3085 (6), 2935 (100), 2870 trans-249D.-"CrH31N"; ion trap m/z 250 (5), 248(1), 206(100), 180(6), 164(2), 136(5), 67 (19), -"C,-H3,N"; ion trap m/z 250 (15), 244 (6), 220 (2), 206 (29), 180 (100), 150 (5), 124 (10), 121 (10), 111 (12), 95 (13), 81 (25), 67 (29), 56 (34), 55 (22); ID; ir 3084 (5), 2934 (100), 2870 (44), 1646 (4), 1453 (14), 1343 (7), 1130 (7), 996 (4), 914 (8) cm"1. rú-275B.-"CigH"N"; m/z 275 (6), 274 (4), 232 (22), 220 (3), 206 (100), 178 (1), 176 (3), 136 (3), 124 (12), 111 (12), 98 (5), 96 (5), 95 (9), 81 (14), 67 (16), 56 (16), 55 (16); ID; ir 3085 (11), 2934 (100), 2868(42),2804(15), 1642 (7), 1448( 16), 1355 (6), 1321 (8), 1089 (5,b), 993 (8), 915 (16) cm"1 (terminal double bond absorptions 308 5,1642,993, and 915 cm"1 are double the intensity of those of OT-249D). The presence of the fragment ion 232 (or 236 after hydrogenation) is not readily rationalized for the proposed structure.…”

“…The structure is tentative. PUMILIOTOXINS, ALLOPUMILIOTOXINS, AND HOMOPUMIUOTOXINS.-Pumiliotoxins.-251D.-,,, ,, ; m/z 251 (18), 250 (10), 208 (10), 206 (6), 194 (40), 176 (6), 166 (100), 70 (48), ID; ir 3543 (11X2967(100), 2886(41), 2797 (35), 1460 (13), 1385 (17), 1313(23), 1155 (19), 1097(16X965(16) cm '; ,-derivative. 267C-QjHjjNOj; m/z 267 (16), 266 (7), 252 (5), 250 (2), 234 (3), 224 (7), 222 (9), 194 (12), 176…”

Indolizidine and quinolizidine alkaloids

“…52 The following indolizidine alkaloids of the pumiliotoxin and allopumiliotoxin classes have now been confirmed in skin extracts from Dendrobates auratus: pumiliotoxins 307A (71) as a mixture of epimers, and 323A (72) ; allopumiliotoxins 253A (73), (tentative assignment), 267A (74), 323B (75) as a mixture of epimers, 339A (76), and 339B (77); and the 0-methyl ether of 323B (78).52 Related alkaloids from D. pumilio whose structures have been elucidated with comparative certainty for the first time (mainly with the help of extensive 13C NMR data) are pumiliotoxins 209F (79) and 225F (80), and allopumiliotoxins 225E (81), 309D (82), and 325A'/325A" (83). 53 The structure of another alkaloid, pumiliotoxin 307F, has been revised to ( 84) from (85) on the basis of NMR magnetization transfer techniques. Compounds previously described as natural products but now considered to be artefacts include pumiliotoxin 307B ( 86) and the 0-methyl ethers of 307A ['pumiliotoxin 321', (87)] and 323B (78), the first perhaps resulting from allylic rearrangement of the OH group in pumiliotoxins 307A' or 307A" [(71), 15-P-OH and 15-a-OH respectively].…”