Angucycline antibiotics

Danishefsky et al. succeeded in preparing the benz[a] anthracene core structure 111 of angucycline antibiotics by performing a benzannulation reaction with the cycloalkynone 109 [69]. Deprotonation of the naphthoquinone 110 with DBU yields the desired anthraquinone 111 (Scheme 49). 

A synthesis of the chlorinated angucycline antibiotic BE-23254 (1686), which was isolated from Streptomyces sp. A 23254, has confirmed the structure of this benz[a anthraquinone derivative (1644,1939,1940). Two detailed examinations of the rare Australian soil actinomycete Kibdelosporangium sp. uncovered a series of... 

D-Olivose (2,6-dideoxy-D-arahiKo-hexose, 55D) is part of the glycosidically linked hexasaccharide in Landomycin A (66),144 a member of the angucycline antibiotic family.145... 

Andrews and Larsen also carried out Lewis acid catalyzed glycosidations of naphthalene derivatives with anomeric acetates to gain access to the ring systems of the Angucycline antibiotics [156]. Suzuki has also published an account of his work on novel Lewis acid catalysts in organic synthesis [157]. 

Another example where DMP reagent worked well while other oxidation methods proved unsuccessful was with the angucycline antibiotic framework.21 Oxidation of the secondary alcohol (46) to the desired ketone (47) adduct proceeded smoothly using DMP. However, compound 47 was found to be labile under other oxidation conditions (Swem, PCC, PDC) causing the epoxide to open and subsequent aromatization of the B ring to occur. 

This reaction is generally used for the preparation of tricyclic systems containing an iminium ion. In addition, this reaction has been used to synthesize the single diastereoisomer of c/5 -l,2-dideoxy-C-glucosides. Other synthetic applications of this reaction, such as the preparation of angucycline antibiotics, have been published. 

Angucycline antibiotic. Prod, by Streptosporangium roseum. Inhibitor of endothelin converting enzyme. 

Angucycline antibiotic. Isol. from Nocar-dia sp. Active against gram-positive bacteria. Orange cryst. (hexane/ Me2CO). Sol. MeOH, CHCI3 poorly sol. H2O. 

The Franck group has also reported on the use of the Bradsher cycloaddition reaction for the generation of a functionalized B-ring of angucycline antibiotic sakyomicin A, 26. Their approach began with the cycloaddition reaction of 27 with the TBDMS enol ether of acetaldehyde to generate adduct 28. A short sequence transformed this compound into 29, the first synthetic model for the dihydronaphthalene framework of 26. 

An FC alkylation with bromolactone 11 is the key step in the first total synthesis of the angucycline antibiotic ( )-brasiliquinone B (Scheme 2.2) [2]. The key tetralin derivative 10 was prepared from 7-methoxytetralone (7) in four steps. The FC reaction between 10 and 11 was carried out in the presence of excess SnCl to afford regioselectively lactone 12 [3], which was reductively opened to give acid 13. Cyclization of 13 with TFAA followed by oxidation with CrO gave brasiliquinone B dimethyl ether (15) in good yield. Reaction of 15 with AlCl brought about demethylation to afford ( )-brasiliquinone B (16). 

Landomycins are new angucycline antibiotics from a streptomyces strain landomycins A-D have been investigated by 2D n.m.r. the... 

The biosynthesis of angucycline antibiotics urdamycins A-D has been studied feeding S. fradiae with [l- " c]-glucose showed that... 

The C-ribosyl naphthoquinone exfoliamycin (24) has been isolated from Streptomyces exfoliatus, along with the products of 0-methylation and of elimination of water in ring C. The structure was determined by X-ray crystallography of a derivative the absolute configuration was not determined, but is assumed to correspond with o-ribose. The first synthesis of angucycline antibiotic Cl04 (26) has been accomplished the key intermediate 25 was made by... 

Further studies on the structure of the angucycline antibiotics urdamycins B-F have been reported they show minor differences in the aglycone compared with urdamycin A (see Vol.20,p.191)... 

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