Otsuka, H.; Shoji, J. published the artcile< Structure of triostin C>, Reference of 5182-90-1, the main research area is .
Triostin antibiotics from a streptomyces related to Streptomyces aureus gave a mixture of components C and A. The mixture (600 mg.) chromatographed on silica gel and eluted with CHCl3-MeOH solutions containing increased concentrations of MeOH from 0-3% and with control by observation of optical densities at 243 mμ, the antibiotic fractions examined by thin-layer chromatography on Al2O3 (solvent, lower layer of 3:1:3 EtOAcCl2CHCHCl2-H2O) and the concentrates containing component C crystallized from CHCl3-MeOH gave 280 mg. triostin C (I), decomposing above 260°, [α]24D -143.9 ± 2° (c 1.121, CHCl3), mol. weight 1125 (Barger-Niederl, CHCl3), 1120 (osmometry, CHCl3). I hydrolyzed 20 hrs. in 6N HCl at 105° and the hydrolysate examined by 2-dimensional paper chromatography gave 4 ninhydrin pos. substances, Rf in 4:1:2 BuOH-AcOH-H2O (and H2O-saturated PhOH): N,N’-dimethylcycstine (II) 0.18 (0.84); alanine (III) 0.36 (0.56); N,γ-dimethylalloisoleucine (IV) 0.74 (0.92); serine (V) 0.26 (0.37). When developed with a collidine-containing MeOH ninhydrin solution (CA 59, 9550a) the spots were brownish-purple, purple, brownish-purple, and grayish-purple. II and IV gave red spots with p-O2NC6H4COCl-C5H5N, indicative of N-alkyl amino acids, and II gave also a red spot with Na2Fe(CN)5NO.2H2O-NaCN. The total acid hydrolysate from 500 mg. I concentrated and extracted with H2O, chromatographed on cellulose and eluted with 4:1:2 BuOH-AcOH-H2O gave in order IV, III, V, II. Similar chromatographic separation on Dowex 50 W × 4 and elution with 0.2M C5H5N-HCO2H (pH 2.80) gave II, V, IV and III in order with partial overlap. The individual acids were isolated by decolorization of the fractions with C and recrystallization to give V, m. 220-5° (decomposition) (H2O-EtOH), [α]24D -14.6 ± 2° (c 0.994, 1.0N HCl); L-III, m. 280-2° (decomposition) (H2O-EtOH), [α]23D 12.1 ± 4° (c 0.626, 1.0N HCl); II, gel-like and difficult to purify, m. 175-82° (decomposition), [α]26D 22.7 ± 2° (c 1.049, 1.0N HCl), [α]25D 34.0 ± 2° (c 1.022, 1.0N HCl), ir spectrum identical with that of synthetic compound, m. 215-17° (decomposition), [α]25D 58.1 ± 2° (c 1.00, 1.0N HCl); L-IV, m. 300°, [α]25.5D 28.4 ± 2° (c 0.937, H2O), 41.9 ± 2° (c 1.049, 5N HCl). II (10 mg.) in 2 ml. H2O stirred 2 hrs. at 45° with 300 mg. Raney Ni and the combined filtrate and H2O-washings examined by paper chromatography on 4:1:2 BuOH-AcOH-H2O, H2O-saturated iso-Pr CH2OH, H2O-saturated Me2CCH2OH, H2O-saturated PhCH2OH, and H2O-saturated PhOH showed Rf values of 0.40, 0.22, 0.06, 0.15, and 0.84 resp., identical with those of synthetic DL-MeCH(NHMe)CO2H. I (500 mg.) partially hydrolyzed in concentrated HCl at 37° 2 days and extracted with EtOAc, the aqueous layer examined for amino acids and the decolorized extract chromatographed on paper with BuOH saturated with 3% aqueous NH4OH as solvent gave quinoxaline-2-carboxylic acid (VI), m. 210-11° (decomposition), ir spectrum identical with that of synthetic VI. I (4.100 mg.) in 0.5 ml. 6N HCl heated 72 hrs. at 105° in an evacuated sealed tube and the hydrolysate submitted to amino acid analysis showed the presence per mole I of 1.48 moles V, 2.02 moles III, 2.16 moles half II, and 2.14 moles IV. A larger amount of V was obtained under milder conditions of hydrolysis. I (2.160 mg.) heated 20 hrs. in 0.3 ml. 5N NaOH at 105° and adjusted with Dowex 50 W (H type) to pH 8.2, acidified with dilute HCl and analyzed gave 0.083 moles V, 1.98 moles III, 1.67 moles IV, and 0.74 mole NH3 per mole I. Extraction of a portion of the hydrolysate with EtOAc gave VI. I (100 mg.) in 6 ml. 90% MeOH containing 0.1N Na0H stirred 2 hrs. at 25° and diluted with 40 ml. H2O, adjusted to pH 2.0 and extracted with EtOAc, transferred into 15 ml. 5% NaHCO3 and reextracted with EtOAc at pH 2.0, the washed extract concentrated and diluted with C6H14 gave 93 mg. alkali-treated triostin C (VII), m. 159-62°, mol. weight 1300 (osmometry, CHCl3), 1000-1300 (Barger-Akiya, Me2CO), pKa 5.7, giving only 0.065 mole V, 1.98 moles III, 2.04 moles half II, 2.06 moles IV, and 2.32 moles NH3 in acid hydrolysis, suggesting the formation of a dehydroalanine derivative by β-elimination reaction on the O-substituted serine residue caused by alkali treatment. VII (15 mg.) heated 3 hrs. at 100° in 0.5 ml. 3N HCl gave 1.8 mole pyruvic acid as determined as its 2,4-dinitrophenylhydrazone, m. 218-20° (MeOH-H2O). VII in 1:1 dioxane-H2O boiled at pH 2.0 released quinoxaline-2-carboxamide, m. 204.5-5.5°. Dakin-West degradation of VII showed that IV was the C-terminal amino acid. VII dinitrophenylated and submitted to acid hydrolysis failed to give dinitrophenylated amino acids, indicating that VI was attached to N-terminal amino acid. Accordingly a lactone linkage was presumed to exist in I. CrO3 oxidation of I did not destroy V, indicating that the OH group of V was involved in the lactone linkage. I (100 mg.) in 2 ml. HCO2H kept 16 hrs. at 0° with 20 ml. performic acid reagent according to Thompson (CA 49, 4748a) and the mixture diluted with 80 ml. H2O, freeze-dried and the residue extracted with MeOH, precipitated with Et2O and the 80 mg. hygroscopic powder analyzed showed the presence of III, IV, V, and N-methylcysteic acid (VIII). I (100 mg.) in 15 ml. 4:1 dioxane-H2O stirred 4.5 hrs. with 1.0 g. Raney Ni W-2 at 80-90° and the filtered solution and washings evaporated, the residue extracted and the extract diluted with C6H14 gave 68 mg. dethiotriostin C (IX), m. 183-6° (decomposition), mol. weight 940, 1000-1300, hydrolyzed to give 1.48 moles V, 1.90 moles III, 2.00 moles N-methylalanine (X), and 1.99 moles IV. I gave no reaction with Na2Fe(CN)5NO-NaCN reagent but a pos. reaction for the disulfide bond was obtained following treatment with cold, dilute NaOH with opening of the lactone ring and increasing solubility The mol. weight determination of IX confirmed a proposed partial formulation and it remained to elucidate the amino acid sequence between IV and V. IX was partially hydrolyzed by concentrated HCl at 37° 2 days and the hydrolysate extracted with BuOH to sep. chromophore and simple peptide fragments. The chromophore peptides, characterized by uv absorption, were separated on a 2-dimensional paper chromatogram in BuOH saturated with aqueous NH4OH followed by 1.5M phosphate buffer, pH 5.0, giving N-(quinoxaline-2-carboxyl)serine and N-(quinoxaline-2-carboxyl)serylalanine, N-(quinoxaline-2-carboxyl)-O-(N,γ-dimethylalloisoleucyl)serine and N-(quinoxaline-2-carboxyl)-O-(N,γ-dimethylalloisoleucyl)serylalanine. As simple peptide fragments, serylalanine and serylalanyl-N-methylalanyl-N,γ-dimethylalloisoleucine were separated by paper chromatography in BuOH-AcOH-H2O followed by H2O-saturated phenol. Similar acid hydrolysis with I gave another 2 peptide fragments consisting of V, III and N,N’-dimethylcystine. It was concluded that I has the proposed structure. There are 2 series of quinoxaline antibiotics; one has a dithiane ring as in echinomycin, and the other contains an N,N’-dimethyl residue. Each series involves several antibiotics differing only in their N-methylamino acid constituents.
Tetrahedron published new progress about 5182-90-1. 5182-90-1 belongs to class quinoxaline, and the molecular formula is C9H7N3O, Reference of 5182-90-1.
Referemce:
Quinoxaline – Wikipedia,
Quinoxaline | C8H6N2 | ChemSpider