Antimicrobial substances of sponges. IV. Structure of a bromine-containing compound from a marine sponge

Abstract

From a marine sponge Verongia fistularis and related species3 we isolated four compounds: A, mp 195°; B, mp 191°; C, mp 132°; and D, mp 137°. The structure and synthesis of compound A, mp 195°, having a broad antibacterial spectrum, was reported in a recent paper.4 A comparison of the ir, nmr, and mass spectra of compound C, molecular formula C29H50O, mp 132°, [a]20n -38.7, with those of /3-sitosterol5 revealed them to be identical. Now we wish to report the evidence leading to structure 1 for compound B, mp 191°. This compound was analyzed for CkHisNOiBi^and showed infrared bands (8) L. F. Feiser and M. Feiser in "Reagents for Organic Synthesis,"

Structures of 2-(3,5-dibromo-4-butoxy-1-hydroxy-4-methoxy-2,5-cyclohexadien-1-yl)ethanamide (I) and 2-(3,5-dibromo-1-hydroxy-4,4-dimethoxy-2,5-cyclohexadien-1-yl)ethanamide (II). Two marine compounds

“…A similar anti-anti conformation of acetals in sterically hindered 1,4-cyclohexadiene rings has been reported by Norskov-Lauritsen, Larsen, Ettlinger & Jaroszewski (1982), versus the gauche-gauche conformation found in 3,3,6,6-tetramethoxy-l,4-cyclohexadiene (Liebich, Yvon & Margaretha, 1976). Compound (II) is also found in Verongia fistularis (Sharma, Vig & Burkholder, 1970).…”

Natural Guanidino Compounds

“…The structure initially proposed was based on chemical and physical data (Forenza et al, 1971) and later corrected following synthesis of the compound (Garcia et al, 1973). 4-Bromophakellin (74a) and 4,S-dibromophakellin (74b) were obtained from the australian sponge Phakellia flabellata (Sharma et al, 1970;Sharma and Burkholder, 1971). They were assigned a tetracyclic structure on the basis of NMR spectra, X-ray diffraction analysis and chemical studies (Sharma and Burkholder, 1971;Sharma and MagdoffFairchild, 1977).…”

The Marine Bromotyrosine Derivatives

“…There were no reports provided for these secondary metabolites again until 1967, when Sharma and Burkholder isolated 2,6-dibromo-4-acetamide-4-hydroxycyclohexadienone (1) and the dimethoxyketal 2 from two marine sponges Verongia fistularis and V. cauliformis (2)(3)(4). Since then, driven by the diverse bioactivities, more and more bromotyrosine-derived marine natural products have been reported.…”