Quinone antibiotic

There are a number of recent studies which, though not aimed specifically at determining the mechanism of desorption, point the way to future experiments in this area. FAB of quinone antibiotics (43) appears to be accompanied by reduction. Quinones with low... 

Fremy s salt (potassium nitrodisulfonate) is a widely used reagent, particularly in the synthesis of quinone antibiotics. One example has emerged from Kozikowski s group in their approach to the rubra-dirin antibiotics. The MEM-protected 2-nitroresorcinol (4) was converted in several steps to the phenol... 

The epoxidation of dienes using MMPP occurs, as expected, at the more electron rich double bond, like those reactions using MCPBA. The example shown in Eq. (7) was one of the stages in a synthesis of the quinone antibiotic frenolicin and used MCPBA in the presence of 5% aqueous sodium hydrogen... 

Allylsilanes have surfaced as excellent reagents for the allylation of a variety of electrophiles. This reaction was employed as a key step in the preparation of pyranonaphtho-quinone antibiotics. One such example is shown in equation 6369. 

Spores of Actinomadura verrucosospora subsp. neohibisca, a producer of the dihydrobenzonaphthacene quinone antibiotic pradimicin, were mutagen-... 

The effects of ammonium ion on the production of the benzoisochromane quinone antibiotic nanaomycin was studied using Streptomyces rosa [106]. Additions of small amounts (15 mM) of ammonium ion increased the production of nanaomycin, while larger... 

Studies on thebiomimetic synthesis of quinone antibiotics [191] led Krohn to yet another type of enantioselective transformation, namely microbial conversion of an achiral substrate into enantiomericaUy pure anthracych-nones. An adroit synthesis of the microbial transformation substrate, 4-deoxyaklanonic acid (202) [192] (Scheme 38), started from homophthahc ester 196 [193] with addition of diUthiated tert-butyl acetoacetate (197) and subsequent cychzation to isocoumarine 198 [194]. Reaction of 198 with the dilithium salt 199 gave anthrone 200 [195[. Aeration of 200 in the pres-... 

Lavemtamycin. C22H14N4O4, Mr 398.38, dark red crystals, mp. >300 °C. A quinone antibiotic from Strep-... 

Quinone antibiotics of the angucyclin/angucyclinone type from cultures of Nocardia and Streptomyces sp. Acid hydrolysis of S. A furnishes S, B as aglycone and D-rhodinose. S. C is 2-deoxy-S, A, S. D is the 5,6-di-hydro derivative of the aglycone S. B, S. E is the 5-methylthio derivative of S. A. All S. are yellow-red, optically active compounds with antibacterial activity, S. A is also active against AIDS viruses and S. E has cytostatic properties. 

C25H22N4OS, Mr 506.47, an aminoquinoline quinone antibiotic isolated for the first time in 1960 from Streptomyces flocculus and other streptomycetes it is structurally related to lavendamycin, forms coffee-brown to black platelets (mp. 275 °C) or brown needles (mp. 262-263 °C). The antibiotic activity of S. is based on an impairment of the matrix function of DNA by covalent bonding in the ratio antibiotic DNA base pairs of 1 2000 and single strand cleavages. S. also exhibits antitumor activity and immunosuppressive properties, it is used as an inhibitor of reverse transcriptase of retroviruses LD50 (dog p.o.) 0.5 mg/kg, (mouse p.o.) 2.3 mg/kg. 

In some cases, the t -complex 8.50 is labile and decomplexes under the reaction conditions, in other cases the free arene can only be obtained by oxidative decomplexation. As the free arene is highly electron rich, however, this is usually accompanied by oxidation to the quinone 8.51 (Scheme 8.17). As there is considerable interest in quinone antibiotics, this can be an advantage On the other hand, decomplexation may sometimes be achieved by heating with CO. This procedure generates Cr(CO)6 as a by-product, which may be recovered. 

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