Some Metabolic Products of Basidiomycetes 5 



diatretyne nitrile, 16 ' 22 and two newly isolated polyacetylenes from 

 Coprinus variegatus. 23 



The polyacetylenes, intensively investigated by synthesis, were al- 

 most unknown in biological material until quite recently. They have 

 now been isolated from higher plants, from fungi {Basidiomycetes) 2i 

 and from Actinomycetes. 25 The probable isolation of propiolic acid 

 from a bacterial culture has also been reported. 26 Matricaria ester and 

 its corresponding alcohol, originally isolated from higher plants, 27 have 

 been obtained from cultures of the basidiomycete, Polyporus anthro- 

 cophilus Cke. 28 



Although polyacetylenes containing as many as eight conjugated 

 triple bonds have been synthesized,* structural variety is better repre- 

 sented in the biologically produced polyacetylenes, some of which 

 contain groupings not yet synthesized. Most polyacetylenes of bio- 

 logical origin contain double bonds as well as conjugated triple bonds; 

 several contain an allene grouping, and some a benzene ring. Carlina 

 oxide, a monoacetylenic compound, contains both a benzene ring and 

 a furan ring. 29 Among the functional groupings which have been 

 found, alone or in combination, are: hydroxyl, carbonyl, carboxyl, 

 ester, amide, lactone, and most recently, nitrile. An unbroken series 

 of polyacetylenes with chain lengths C 8 to C 13 have been reported 2i 

 in addition to the Ci 7 and C 18 compounds. 



Nemotin and nemotin A, the first of the polyacetylenes characterized 

 in our laboratory, were not immediately recognized as such,f although 

 they had been studied spectrophotometrically and the characteristic 

 alkali conversion of nemotin to nemotin A had been examined in some 

 detail. 16 It was only after application of the too-little-known rule of 

 Hausser, Kuhn, and Seitz 30 on spacings of the absorption maxima of 

 polyacetylenes and polyethylenes, about 65/ for polyacetylenes and 

 37-47/ for polyethylenes, that these compounds, as well as the rest of 

 the series, were placed in the polyacetylene group. 



The chemistry of nemotin has proved to be of considerable interest. 

 The ultraviolet absorption spectrum of this polyacetylene indicated 

 an endiyne system of unsaturation. On reduction, nemotin yielded 

 undecanoic acid. Since nemotin itself was not acidic, it was postulated 



*The synthesis of diphenyloctaacetylene was reported from the laboratory of 

 E. R. H. Jones, Nature, 168, 900 (1951). 



t A remark by Sorensen seems appropriate here. In discussing Semmler's pref- 

 erence for an allenic rather than one of the possible acetylenie structures for 

 carlina oxide, he says that Semmler, "led by an irrational aversion against the 

 occurrence of the acetylenic compounds in nature . . . ," chose the wrong formula. 



