Cassane diterpenes

Cleistanthol (42), isolated from Cleistanthus schlechteri, is an unusual diter-pene. In contrast to the cassane diterpenes, its structure results from formal... 

Zhang JY et al (2013) Caesanines A-D, new cassane diterpenes with unprecedented N bridge from Caesalpinia sappan. Org Lett 15 4726 729... 

Schaller, F. Rahalison, L. Islam, N. Potterat, O. Hostettmann, K. Stoeckli-Evans, H. Mavi, S. A new potent antifungal quinone methide diterpene with a cassane skeleton from Bobgunnia madagascariensis. Helv. Chim. Acta 2000, 83, 407-413. 

Cassanes.— -Caesalpin (41), from Caesalpinia pulcherrima, possesses the cassane skeleton, and is thus related to the bitter principles isolated from the seeds of Caesalpinia bonducella. Cassminic acid is a minor constituent of the bark of Erythrophleum guineense. Spectroscopic measurements and an interrelationship with cassane-16,19-dioic acid have established " it as 6-oxo-7-hydroxycass-13-ene-16,19-dioic acid. N.m.r. measurements and bromination-dehydrobromina-tion studies are in accord with the axial 14a-configuration now accepted for the cassamic acid diterpenes. 

Examples of diterpenes with the cleistanthane and cassane skeleton have been isolated from an unidentified sterile coprophilous fungus. Sonomolide A and B (162, 163) display antifungal activity against Aspergillus fumigatus and Candida albicans but do not show antibacterial activity towards Bacillus subtilis [229]. 

Cassane and Miscellaneous Tricyclic Diterpenoids.—A group of furanoid diterpenoids, related to the caesalpins, has been isolated from Pterodon emargina-and P. pubescens. They include compounds (39—42). Some further diterpene alkaloids of the cassaic acid class have been isolated from Erythro-phleum ivorense. 

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