3.5- Dibromo-4-hydroxybenzyl alcohol

The several known polybrominated diphenylmethanes (1) may arise via a pathway analogous to the known dimerization of benzyl alcohols (1754). For example, the red algal known metabolite 3,5-dibromo-4-hydroxybenzyl alcohol may condense to give the known thelephenol (EEE) via (non-enzymatic) ipso electrophilic substitution (Scheme 3.4). These condensations can occur under mild acidic conditions (1754). 

Tadesse and coworkers assumed that pulmonarins and synoxazolidinones share the common biosynthetic route in the organism [15]. Pulmonarin A (19) had been considered as a dibrominated form of />-hydroxybenzoylcholine, which biosynthetically derived from p-hydroxybenzyl alcohol [16, 17]. According to the proposed biosynthesis dibromo hydroxybenzyl alcohol 21 get oxidized and methylated before coupling with choline 24 (Scheme 3). The biosynthesis of pulmonarin B (20) was assumed via the coupling of known metabolites 2-(3,5-dibromo-4-methoxyphenyl)acetic acid 25 [11] and ascophylline 26 [18]. 

About 30 brominated derivatives have been identified in marine cyanobacteria. In each of these cases, bromine atoms are fixed on a benzene nucleus, a bis-indolic system, or on a linear chain, but always in the vinylic position. The two simplest compounds are lanosol and 3,5-dibromo-p-hydroxybenzylic alcohol, both isolated from the species Calothrix brevissima (Pedersen and Da Silva, 1973). 

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