Metabolites of pyrenomycetes. XIV: Structure and partial stereochemistry of the antibiotic macrolides hypothemycin and dihydrohypothemycin

Based on spectroscopic data and chemical degradation, hypothemycin and dihydrohypothemycin, two antibiotic metabolites of $\text{Hypomyces}$$\text{trichothecoides}$ have been assigned the macrolide structures 1 and 2. Partial stereochemistry of these compounds was determined usinq Two-Dimensional J proton spectrum and extensive decouplinq experiments.     

Synthesis of the antifungal macrolide antibiotic (+)-roxaticin

The total synthesis of the antifungal macrolide antibiotic roxaticin has been accomplished. The synthesis relies principally on aldol and directed reduction steps to construct the extended 1,3-polyol array present in the natural product. Three principal nonpolyene containing fragments were assembled and then coupled using Julia olefination and methyl ketone aldol addition reactions. A series of functionalization reactions incorporated the sensitive polyene and provided the protected roxaticin seco-acid, which was lactonized in good yield. Acidic deprotection completed this convergent synthesis of roxaticin.     

Metabolites of pyrenomycetes XI. Structure of Aurocitrin,a new antibacterial pigment from Hypocrea citrina.

Isolation and structure elucidation of aurocitrin, a new antibiotic metabolite from two varieties of the hypocrealean fungus, H. citrina, is reported.     

Structure of neooxazolomycin,an antitumor antibiotic

Based on the spectroscopic analysis and correlation with the degradation products of oxazolomycin, the structure of neooxazolomycin has been elucidated.     

Structure of an antitumor antibiotic,reductiomycin

The structure of an antitumor antibiotic isolated from a variant of $\text{Streptomyces orientalis}$ was established as ($\text{1}$) by chemical and spectral evidence. The antibiotic was found to be identical with reductiomycin, and therefore the structure (X) of reductiomycin previously reported must be revised.     

Total synthesis of rutamycin B, a macrolide antibiotic from Streptomyces aureofaciens.

Rutamycin B (2) was synthesized from three principal subunits, spiroketal 75, keto aldehyde 83, and aldehyde 108. First, triol 62 was assembled by Julia coupling of sulfone 56 with aldehyde 58 followed by an acid-catalyzed spiroketalization. The three hydroxyl functions of 62 were successfully differentiated, leading to phosphonate 75. The latter was condensed in a Wadsworth-Emmons reaction with 83, prepared in six steps from (R)-aldehyde 76, to give 92. Coupling of the titanium enolate of 92 with 108 afforded Felkin product 109 with high stereoselectivity in a process that is critically dependent on the presence of the p-methoxybenzyl ether in the aldehyde. Transformation of 109 via aldehyde 116 to vinylboronate 122 was followed by macrocyclization under Suzuki conditions to yield 123. Exhaustive desilylation of the latter yielded rutamycin B.     

Total synthesis of an antitubercular lactone antibiotic, (+)-tubelactomicin A

(+)-Tubelactomicin A (1), an antitubercular lactone, has been synthesized from (S)-citronellol (2) and 2-deoxy-l-ribonolactone (18) through intramolecular Diels-Alder reaction, Suzuki-Miyaura coupling, and Shiina macrolactonization.     

Metabolic products of microorganisms. 107. Structure of the chlorothricins, a new macrolide antibiotic

Chemical and spectroscopic evidence for the structural formula 9 of chlorothricolide methyl ester, derived from the aglycone of the antibiotic chlorothricin, is given. By chemical degradation and spectroscopic investigations structure 41 is deduced for the intact antibiotic.     

The structure of tetramycin,a new polyene macrolide antibiotic

The structure of the tetraene antifungal antibiotic tetramycin has been established by detailed studies of mass, ¹H and ¹³C NMR spectra as well as by chemical degradation. A newly developed mass analysis has been introduced for determining the carbon skeleton of the aglycone.     

Colubricidin A, a novel macrolide antibiotic from a Streptomyces sp.

A new 34-membered macrolide antibiotic, colubricidin A (1), was isolated from the fermentation broth of a new streptomyces species. Its structure was elucidated on the basis of analysis of the spectroscopic data and chemical degradation. It was identified as a glycomacrolide with an unprecedented aromatic chromophore. Colubricidin A showed excellent activity against Gram-positive bacteria.     

Synthesis of Aristotelia-Type Alkaloids. Part XIII. Total syntheses of (+)-makonine, (+)-aristotelinone,and (+)-11,12-didehydroaristoteline

The oxidative transformation of synthetic (+)-aristoteline ((+)- 6 ) into other metabolites which had been isolated from Aristotelia species was investigated. Thus, treatment of (+)- 6 with I₂ as the single oxidant furnished the naturally occurring indole alkaloids (+)-makonine ((+)- 9 ),(+)-aristotelinone ((+)- 11 ), or (+)-11, 12-didehydroaristoteline ((+)- 7 ) in good yields, the selectivity of the oxidation process depending on the chosen reaction conditions.     

Asymmetric synthesis of the polyol subunit of the macrolide antibiotic, ossamycin

An asymmetric synthesis of the C1-C16 polyol subunit of the macrolide antibiotic, ossamycin, has been achieved through stepwise carbon-chain elongation reaction from d-glucose.     

A convergent synthesis of (+)-cryptophycin B, a potent antitumor macrolide from Nostoc sp. cyanobacteria

[structure--see text] An efficient and highly stereoselective synthesis of cryptophycin B (2), a potent cytotoxic agent, is described. The ester-derived titanium-enolate-mediated syn-aldol reaction was employed to generate the stereocenters C(5) and C(6). The route is convergent and provides a convenient access to the synthesis of structural variants of cryptophycin B as well as members of its family.