Structural Assignment of Tetrabromostyloguanidine: Does the Relative Configuration of the Palau'amines Need Revision?

Abstract

Products of the Caribbean: The palau'amine derivative tetrabromostyloguanidine 1 was isolated from the sponge Stylissa caribica and the elucidation of its structure with the focus on the relative configuration is discussed in detail. Results from NMR studies and molecular calculations suggest that the relative configuration for members of the palau'amine family differs from that earlier reported.

Structure of debromo-carteramine A, a novel bromopyrrole alkaloid from the Mediterranean sponge Axinella verrucosa

“…The relative stereochemistry of the eight chiral centres of 2 was suggested to be the same as 3 by comparison of their 13 C-NMR data 23 Thus 2-debromo-carteramine A 2 exhibited the same relative configuration as carteramine A 23 (≡ tetrabromostyloguanidine), 24 the stereochemistry of which was determined by NOESY analysis 26 and computational methods, 24 and differed from those reported for palau'amine and related compounds. 10,11 However, in both these recent papers 23,24 the relative configuration of palau'amine congeners was suggested to need revision.…”

“…10,11 However, in both these recent papers 23,24 the relative configuration of palau'amine congeners was suggested to need revision. Compounds 1 and 2 showed activity against the environmental marine bacterium Lysinibacillus sp.…”

“…Interestingly, the reported at the same time from Stylissa caribica. 24 Carteramine A did not inhibit the bacterium of choice. In this paper, we report the isolation and structure elucidation of the novel compound 2.…”

Disturbance of voltage-induced cellular calcium entry by marine dimeric and tetrameric pyrrole–imidazole alkaloids

“…1), with different structures, grade of bromination and number of amino-imidazol groups, isolated from the marine sponges Stylissa caribica and Agelas wiedenmayeri. The alkaloids 4-bromopyrrole-2-carboxy-N(e)-lysine, 4-bromopyrrole-2-carboxyarginine (Grube et al, 2006), oxocyclostylidol (Grube and Ko¨ck, 2006a), stevensine (Albizati and Faulkner, 1985), massadine (Nishimura et al, 2003), tetrabromostyloguanidine (Grube and Ko¨ck, 2007;Kobayashi et al 2007), stylissadines A and B (Grube and Ko¨ck, 2006b;Buchanan et al, 2007) (S. caribica), mauritiamine (Tsukamoto et al, 1996), ageladine A (Fujita et al, 2003) (A. wiedenmayeri), and cyclooroidin (Fattorusso and TaglialatelaScafati, 2000;Po¨verlein et al, 2006) were used in this study to obtain an insight into the structureactivity relationship of bromopyrrole alkaloids with the cellular Ca 2+ homeostasis in PC12 cells.…”

Synthetic Access to the Chlorocyclopentane Cores of the Proposed Original and Revised Structures of Palau′amine

“…[18][19][20][21][22][23][24][25] The construction of the central chlorinated cyclopentane skeleton within 1, with control over the relative stereochemical configuration of all of its substituents, emerges as a demanding challenge in this synthetic target. This synthetic hurdle is further complicated by the recent discovery highlighting the stereochemical revision of palau'amine [26][27][28][29] based on NMR spectroscopy, molecular calculations, and comparison to related natural products. These data suggest that the endo-disposed C17 chloro group and the C12 cis-fused ring junction in the originally proposed structure 1a instead exists as its C12,C17 diastereomeric counterpart 1b, which incorporates a rare trans-fused [3.3.0]-bicyclic skeleton.…”