Miscellaneous Bromo-Compounds

Minale, G. Cimino, S. De Stefano and G. Sodano oroidin acetate H2, Pd/C dihydrooroidin acetate 

More recently Stempien et al. have announced 173) the occurrence in an unidentified species of Agelas of a further bromopyrrole derivative with antibiotic activity, to which they assigned the structure 4-bromo-pyrrole-2-carbonylguanidine (31). 

Two brominated phenoxyphenols, active against both gram-neg. and gram-pos. organisms, have been found in Disidea herbacea 166) and structures (32) and (33) were assigned. Both structures were based on the conversion of these substances by catalytic hydrogenolysis into the known 2-hydroxy diphenyl ether, and on analyses of their n. m. r. spectra. 

The structure of the pentabromo constituent was also confirmed by synthesis 2,4-dinitrochlorobenzene was condensed with 3,4,5-tribromo-guaiol and the nitro groups of the resulting ether were reduced to give the diamino derivative. Sandmeyer reaction on the latter finally gave l-(2, 4 -dibromophenoxy)-2-methoxy-4,5,6-tribromobenzene, which was identical with the methyl ether obtained from the natural substance. 

Two new antibacterial bromoindole metabolites have been isolated from the Caribean sponge Polyfibrospongia maynardii 179). Structures (34) and (35) were assigned mainly by interpretation of their spectroscopic properties. In confirmation catalytic hydrogenation of (34) afforded the known 3-(2-methylaminoethyl)-indole. 

---

During the past few years several reports have appeared which describe the occurrence of btomocompounds also in sponges and now the Porifera phylum appears as one of the richest sources of bromine-containing metabolites. The next subsection considers the tyrosine-derived bromo compounds the bromopyrrole derivatives and miscellaneous metabolites are reviewed in subsection 1.2. 

Miscellaneous Compounds. A saturated spirocychc pyrrohdine serves as the nucleus for a diamine that has been described as a hypohpemic agent. Treatment of the carbanion of the substituted cylcohexane carboxyhc ester (20-1) with methyl bromoacetate leads to the alkylation and formation of the diester (20-2). Saponification of the ester groups followed by reaction with acetic anhydride leads to ring closure of the succinic anhydride (20-3). Condensation with ammonia leads to the succinimide (20-4). The side chain is then added by alkylation of the anion on nitrogen with l-bromo-4-dimethylaminobutane (20-5). Reaction of this last intermediate with lithium aluminum hydride leads to the reduction of the carbonyl groups to methylene. This affords the pyrrolidine (20-6) atiprimod [22]. 

Miscellaneous Systems Many systems have been mentioned [li,m,2i] acyloxy and acylsilyl phosphine oxides, phosphine sulfides, cyclic compounds, benzoyloxa-ziridine derivatives, dibenzoylmethane derivatives, triazene and pentaazadiene moiety containing compounds. New developments include benzyl benzoin benzyl ethers [112], dithiocarbamates [113], ketoamides [114], phosphonates [115], bromo-acetylpyrene [116], alkylimides [117], aryloxy naphthalene [118], oligosilanes [119], bisphosphine sulfides [120], sulfamic esters of benzoin ethers [121], sulfur [122], or carbohydrate [123] containing compounds. 

As was the case for 5-exo-cyclizalions, aside from the more frequently encountered substructures that undergo 6-exo-cyclization, many miscellaneous examples can be found throughout the literature [118-120]. One study concerns the effect of the stereochemistry of vinyl bromo substrates 158 and 160 on the ratio of possible double-bond isomers in the product (Scheme 6.46) [121]. Starting from the cw-compound 158, bisunsaturated indolizidinone 159 was obtained along with only traces of the bis-exo-cyclic diene. The tran -compound 160 reacted twice as fast and gave a 4 1 mixture of 161 162. Product 161 is probably the first to be formed, and its more stable isomer 162 is most likely formed by a readdition and elimination of HPdBr. 

Sulphonium ylides react with a variety of miscellaneous electrophilic reagents. Barney has reported that dimethylsulphoniumcyclopenta-dienylide (3) will form complexes with a variety of metal salts, such as Hgl2, ZnCU, and AgNOa, with some co-ordination occurring with the ring and some with the sulphur. Dimethylsulphoniumphenacylide reacted with isopropyl nitrite to afford the bromo-keto-oxime (52), probably the result of ylide attack on nitrogen, isomerization of the nitroso-compounds to... 

---