Pfizer Handbook of Microbial Metabolites 400 



855 Ipomeamarone, C15H20O3, colorless oil, b. 0.001 103°, ric^^ 1.4827, 

 [<x]u-' +28°. 



-CH CH2 



1 I 



O CH2 



U 



CH3 C— CHo— CH2— CH 



CH3 



CH3 



Ceratostomella fimbriata (sweet potato substrate) 



T. Kubota and T. Matsuura, Chem. and Ind., 521 (1956). 

 (Synthesis) 



There is a marked resemblance between ipomeamarone 

 and dendrolasin, an oil Ci.r.HoL.O, isolated from ants. It is 

 an enantiomer of ngaione, isolated from Myoporum spp. 

 (higher plant). 



A. Quilico, F. Piozzi and M. Pavan, Tetrahedron 1 177 

 (1957). (Structure) 



A. J. Birch, R. A. Massy-Westropp and S. E. Wright, Chem. 

 and Ind., 902 (1954). 



Ipomeamarone is thought to be formed by the host 

 (sweet potato) tissue to resist invasion by Ceratostomella 

 fimbriata.* 



b. DIBENZOFURANS AND RELATED SUBSTANCES 



Dibenzofurans constitute a class of natural products 

 found only in lichens. Usnic acid is the most widely dis- 

 tributed dibenzofuran. Its structure, which was contro- 

 versial for some time, now has been proved by synthesis.^ 

 The dibenzofurans are formed from 2 moles of the ace- 

 tate-derived resorcinolic substances typical of lichens. 

 Results of chemical experiments, including the method of 

 synthesis of usnic acid, make it quite probable that phenol 

 coupling of the sort mentioned in connection with dep- 

 sides and depsidones also is involved here.-' ^ Thus, 



* T. Akazawa, Arch. Biochem. and Biophys. 90 82 (1960). 



1 D. H. R. Barton, A. M. Deflorin, O. E. Edwards and J. B. Hen- 

 drickson, Chem. and Ind., 1670 (1955). 



2 D. H. R. Barton and T. Cohen, Festschr. Arthur Stoll, 117 (1957). 

 ^ Holger Erdtman and Carl Axel Wachtmeister, ibid., 144 (1957). 



