Dendrobatid family

An S 2 copper-catalyzed nucleophilic substitution of the chloride in a cyclic chloroacetate by butylmagnesium bromide was employed in a synthesis toward perhydrohistrionicotoxin [Eq.(47)] [79]. Histrionicotoxins are found in South American dart-poison frogs of the Dendrobatid family. Palladium-catalyzed chloroacetoxylation of 2-substituted diene 68 gave a highly regio- and stereoselective 1,4-addition product where the chloride ends up in the 1-position. Copper-catalyzed reaction of the chloroacetate 69 with butylmagnesium... 

The batrachotoxins were the first class of unique alkaloids to be characterized from skin extracts of frogs of the family Dendrobatidae (see ref. 23 for a review of amphibian alkaloids). Batrachotoxin was detected in only five species of dendrobatid frogs and these frogs were then classified as the monophyletic genus Phyllobates, based in part on the presence of batrachotoxins (24). However, levels of batrachotoxins differ considerably, with the Colombian Phyllobates terribilis containing nearly 1 mg of batrachotoxins per frog, while the somewhat smaller Phyllobates bicolor and Phyllobates aurotaenia, also from the rain forests of the Pacific versant in Colombia, contain 10-fold lower skin levels (8). The two... 

Most amphibian alkaloids are not as complex in structure as the steroidal batrachotoxins and samandarines. Of the 300 known amphibian alkaloids, most have been characterized from the skin extracts of frogs of the family Dendrobatidae and, hence, have been referred to as dendrobatid alkaloids. The major bicyclic classes of dendrobatid alkaloids are the histrionicotox-ins, decahydroquinolines, and pumiliotoxin-A class. Because of the presence of a piperidine ring in most dendrobatid alkaloids, they also have been referred to as piperidine-based alkaloids. 

The pseudophrynamines are only known from seven species of the genus Pseudophryne in the family Myobatrachidae (205). However, almost all Pseudophryne species investigated also contained the well known dendrobatid alkaloids pumilotoxins in some populations they could not be detected. Pseudophrynamines were the dominant alkaloids in two species (P. guentheri and P. occidentalis) from Western Australia, while all five eastern species contained significant amounts of pumilotoxins as well. It is interesting to note that the pseudophrynamines vary like the bryozoan alkaloids and that they were the main alkaloids only in some populations of the same species. 

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