HPLC of antibiotics. 1. Streptolydigin and related compounds

Two new acyltetramic acids related to streptolydigin have been isolated from fermentations of Streptomyces lydicus. The principal members of this complex were resolved by TLC on silica gel. However, the methods of detection, permanganate spray or bioautography, were not suitable for both crude fermentation broths and purified extracts. Gas chromatography is unsuitable for the detection of either underivatized or silylated streptolydigins. High performance liquid chromatography (HPLC) particularly on triethylaminoethyl cellulose is rapid and sensitive and is the method of choice for the analysis of both crude and purified samples. Using high performance liquid chromatography, two components were detected in the complex, which are not observed using any of the other chromatographic procedures.     

Polyimidazopyrrolones and related polymers. I. Dianhydrides and o-acetamidodiamines

Solutions of polyimidazopyrrolone precursors prepared by reaction of tetraamines and dianhydrides in polar solvents tend to crosslink and gel very easily. Substitution of o-acetamidodiamines for the tetraamines gives stable solutions. A study of cure mechanisms by TGA, infrared, and pyrolysis experiments with polymers and model compounds indicates that the acetylated materials are converted cleanly to imides at 150°C. At temperatures above 350°C, structural changes and further polymerization occur, with little imidazopyrrolone formation. Polymers derived from tetraamines cure by multiple mechanisms but finally yield the imidazopyrrolone structure. The acetylated polymers and copolymers give acceptable laminates but poor films.     

Terpenoids. LIII. Antitumor activity of trichorabdals and related compounds

Among the three types, enmein-, oridonin-, and trichorabdal-type, of diterpenoids from Rabdosia trichocarpa, the latter showed the highest antitumor activity against Ehrlich ascites carcinoma in mice. Their potent activities were attributed to synergistic increase arising from the presence of two active sites in one molecule. In vitro activity against HeLa cells and in vivo activity against P 388 lymphocytic leukemia of diterpenoids and related compounds were also determined, but no synergistic increase in activity due to plural active sites was observed in those cases.     

Substituted pyrimidines. II. 1,3-Dimethylisocytosine and related compounds

1,3-Dimethyl-1,2-dihydro-2-imino-4(3H)pyrimidinone (1,3-dimethylisocytosine) was prepared by methylation of 2-amino-3-methyl-4(3H)pyrimidinone and was degraded in alkaline solution to a mixture of 3-methyl-2-methylamino-4(3H)pyrimidinone, 1,3-dimethyl-2,4-(1H,3H)pyrimid-indione, 2-methylamino-l-methyl-4(1H)pyrimidinone, 1-methyl-2,4-(1H,3H)pyrimidindione and 3-methyl-2,4-(1H,3H)pyrimidindione. Thiation of the title compound gave both 1,2-dihydro-1,3-dimethyl-2-thio-4(3H)pyrimidinone and 1,3-dimethyl-2,4-(1H,3H)pyrimidinedithione. The title compound is a tautomerically fixed pyrimidine and its uv spectra were compared with related compounds, notably 3-methyl-2-dimethylarnino-4(3H)pyrimidinone which is also tautomerically fixed.     

Polysiloxane zwitterionomers and related model compounds. I. Synthesis

Polymers containing zwitterions were prepared by reacting γ-propanesultone with polydimethylsiloxane-co-(4,7-diazaheptylmethylsiloxane), which generated substituted di(ammonium-3-propane-sulfonate) groups pendant from the siloxane chain. Their concentration in the polymers varied from 0.5 to 10 mole %. Two model compounds were also prepared in order to (1) characterize the reaction leading to the formation of these zwitterions and (2) characterize the ionic forces in solutions (tetrahydrofuran and benzene were used as solvents). The degree of aggregation of these model compounds was higher in tetrahydrofuran and increased in both solutions with the concentration. No rearrangements of siloxane bonds were observed in the presence of these zwitterions or γ-propanesultone.     

Pyrimidines. 6. 6-trifluoromethyl chloropyrimidines and related compounds

A study of the chlorination of 6-trifluoromethylpyrimidines was made. On sequential treatment of 6-tri-fluoromethyluracil (6) with phosphorus oxychloride and phosphorus pentachloride, 2,4-dichloro-6-trifluoro-methylpyrimidine (7) (25%) and 4-chloro-6-trifluoromethylpyrimidin-2-yldichlorophosphate (8) (53%) were obtained. Compound 8 was converted to 7 by treatment with hydrogen chloride in phosphorus oxychloride in 72% yield. In a one-pot synthesis, 77% of 7 was obtained from 6. The preparation of 2,4,5-trichloro-6-tri-fluoromethyluracil (16) proceeded similarly. Although the pyrimidinyldichlorophosphate ester has been proposed as the intermediate in converting a pyrimidinol to a chloropyrimidine, these are the first examples of such compounds to be isolated, characterized, and made to yield the ring-chlorinated pyrimidines.     

Photochemistry of ommochromes and related compounds. Part II

The visible light irradiated solutions of the 1-methyl-1-(1′-[11-(β-aspartoyl-methyl ester-imino)]ethenyl]-ketal-1H,5H-pyrido[3,2-a]phenoxazin-5-one ( 1 ) and the 1,5-dimethoxy-11-(β-aspartoyl-N-acetyl-methyl ester)-pyrido[3,2-a]phenoxazine ( 2 ) [1], in methanol and acidic methanol, are examined. Both methanolic solutions undergo light induced transformation according to an opening of the phenoxazinone and phenoxazine systems, not reversible in darkness. On the contrary, 1 and 2 in methanol-acid solutions, under visible light irradiation, yield a solvent photoaddition, reversible in darkness. Some phototransformation products are examined and a plausible mechanism, for the reactions explanation, is suggested.     

Stereocontrolled syntheses of carbocyclic C-nucleosides and related compounds.

Carbocyclic 9-deazapurine nucleosides (1-4), a spiranic pyrimidone carbocyclic compound (5), and an unusual carbocyclic isonucleoside (6) were prepared as enantiomerically pure compounds via the key intermediates 10 and 21 from 1,4-gamma-ribonolactone. The key intermediate 10 was prepared by stereoselective reduction with Bu3SnH and then converted to carbocyclic C-ribonucleosides 1, 3, and 4. 2',3'-Didehydro-2',3'-dideoxycarbocyclic 9-deazainosine (2) was prepared from a 2',3'-dimesylate 17 by treatment with Li2Te followed by an acidic deprotection. The key bicyclic intermediate 21 was prepared from a diol 20 by an intramolecular cyclization using CHI3-Ph3P-imidazole and converted to the spiranic compound 5 and an olefinic nucleoside 6 by the construction of the heterocyclic moiety followed by deprotection.