626 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Journal zyx of Natural Products Vol. 55, No. 5, pp. 626-632, May 1992 zyxwvutsr A FURTHER CI5 NONTERPENOID POLYBROMOETHER FROM THE ENCRUSTING SPONGE MYCALE ROTALZS GIACOMO NOTARO, VINCENZO PICCIALLI, DONATO SICA,+ Dipartimento di Chimica Organica e Biologica, Uniwrsitadi Napoli, Via Mezzocannone 16, 80134 Napoli, Italy LUCIANO MAYOL, Dipartinmto di Chimica delle Sostanze Naturali, Uniwrsitadi Napoli, Via D . Montuano 49, 801 3 I Ndpoli, Italy and FEDERICO GIORDANO Dipartimento di Chimica, Universita di Napoli, Via Mezzournnone 4, 80134 Napoli, Italy ABSTRACT.-A new cyclic polybrominated CIS acetogenin 1 has zyx been isolated from the encrusting sponge Mycale mtalzs, and its structure zyxwv has been determined through a combination of spectroscopic and single-crystal X-ray diffraction analyses and simple chemical transforma- tions. In the course of our systematic studies on Mediterranean organisms, we have inves- tigated the encrusting sponge zyxwv Mycale rotalis Bouterbank (Dernospongiae) and isolated rotalins A and B (l), two new diterpenes. More interestingly we found two polybro- minated C,, acetogenins 2 and 3 (2), typical metabolites of Luurencia genus, in the CHCI, extracts of this animal. We wish to report here that a further investigation of the extractive of M. rotalis led us to the isolation of a new cyclic polybrominated metabolite based on a straight C,, carbon skeleton. The structure of the new compound has been established by a combination of spec- troscopic methods, including 2D nmr, and some chemical transformations and con- firmed by single-crystal X-ray diffraction analysis. Compound 1 was isolated as an optically active crystalline solid {mp 128-130” (from CHC1,); [c~]”D +38.8 (c= 1.3, CHCl,)]. The ei mass spectrum revealed the presence of four bromine atoms in the molecule displaying a cluster of peaks at m/z 564, 566, 568, 570, 572, while the accurate mass measurement established a molecular for- mula of C,,H2003Br4for the new metabolite. All 15 carbons were observed in the 13C-nmr spectrum of 1 recorded in CDCl, solu- tion (Table l), and DEPT experiments demonstrated that 19 protons were attached to zyxwvuts Br 1 2 3