Theodorus van Es

Existence of carcinine, a histamine-related compound, in mammalian tissues

Carcinine (beta-alanylhistamine) was synthesized in vitro from histamine and beta-alanine. It was detected quantitatively using an HPLC method previously described for the quantification of the related compounds histamine, histidine, carnosine and 3-methylhistamine. Carcinine was identified in several tissue of the rat, guinea pig, mouse and human, and was then shown to be metabolically related in vivo to histamine, histidine, carnosine and 3-methylhistamine through radioisotopic labeling. The results demonstrate that carcinine may be concurrently quantitated using the same HPLC method as that used to measure histamine, histidine, carnosine and 3-methylhistamine. These findings suggest a role for carcinine in the carnosine-histidine-histamine metabolic pathway and in the mammalian physiologic response to stress.

Intramolecular cyclization of pentose and hexose dithioacetals

Abstract The intramolecular cyclization of O -tosyl derivatives of dithioacetals of d -ribose, d -arabinose, and d -glucose was investigated. p -Toluenesulfonylation of d -glucose diethyl dithioacetal gave 3,6-anhydro- d -glucose diethyl dithioacetal. Variously substituted 5- O -tosyl- d -glucose dibenzyl dithioacetals gave derivatives of either 2,5-anhydro- l -idose dibenzyl dithioacetal, benzyl 1,5-dithio- l -idopyranoside, or l -idose dibenzyl dithioacetal. Likewise, 4- O -tosyl- d -glucose dibenzyl dithioacetal derivatives gave benzyl 1,4-dithio- d -galactofuranoside derivatives.

Polyoxyethylated cholesterol derivatives Organic synthesis, cellular uptake and effect on lipid metabolism in cultured skin fibroblasts

Abstract Polyoxyethylated derivatives of cholesterol were synthesized by adduction of ethylene oxide to the 3-β-hydroxy position of cholesterol. Derivatives with the methoxy terminal were prepared by condensing methoxypoly(oxyethylene)methane sulfonate with cholesterol. Derivatives with nine ethoxy groups were isolated by the combined use of high pressure liquid chromatography and thin-layer chromatography and identified by proton magnetic resonance. In cultured human skin fibroblasts, uptake of polyoxyethylated [ 3 H]cholesterol was linear up to a concentration of 60 μM. Uptake at 10 μM concentration was linear for 5 h and amounted to 2.5% of the total added label per h. All of the cellular radioactivity was recovered in polyoxyethylated cholesterol and no label appeared in other lipid fractions. Polyoxyethylated cholesterol (10 μM) inhibited the incorporation of acetate into cholesterol and the activity of 3-hydroxy-3-methylglutaryl-CoA reductase, 50% inhibition occurring at 1 and 3 h, respectively. After 18 h incubation, 50% inhibition of both activities occurred at 5 μM and near total inhibition at 25 μM. The incorporation of leucine into protein, uridine into RNA and thymidine into DNA were not affected significantly. Methoxypolyoxyethylated cholesterol gave similar results. There were no differences between normal and homozygous familial hypercholesterolemic fibroblasts which lack membrane receptors for low density lipoproteins. Incorporation of acetate into fatty acids was suppressed by polyoxyethylated cholesterol but not by 25-hydroxycholesterol. Polyoxyethylated cholesterol had no effect on the activity of fatty acid synthetase. Efflux of polyoxyethylated cholesterol from cells had a rapid phase amounting to 55% in the first 2 h, followed by a slow leakage of 15% in the next 20 h. Recovery of the activity of 3-hydroxy-3-methylglutaryl-CoA reductase was faster than that of incorporation of acetate to cholesterol and fatty acids but all these activities remained below the control levels, suggesting that the polyoxyethylated cholesterol retained within the cell continues to exert its inhibitory effect on lipid synthesis.

Selenium derivatives of L-arabinose, D-ribose, and D-xylose

Abstract Attempted cyclization of 2,3,4-tri-O-methyl-5-seleno- L -arabinose dimethyl acetal in acidic solution gave the corresponding diselenide. Intramolecular attack by the selenobenzyl group at C-5 of 5-O-p-tolylsulfonyl- L -arabinose dibenzyl diseleno-acetal resulted in the formation of benzyl 1,5-diseleno- L -arabinopyranoside. Similarly, 2,3,5-tri-O-methyl-4-O-p-tolylsulfonyl- D -xylose dibenzyl diselenoacetal gave benzyl 2,3,5-tri-O-methyl-1,4-diseleno- L -arabinofuranoside, and 2,3,4-tri-O-acetyl-5-O-p-tolylsulfonyl- D -xylose (or ribose) dibenzyl diselenoacetal gave benzyl 2,3,4-tri-O-acetyl-1,5-diseleno- D -xylo- (or ribo-)pyranoside. The glycosylic benzylseleno group was removed from the pyranoside with mercuric acetate, but attempted deacetylation of the product led to decomposition and not to the expected 5-seleno- D -xylopyranose.

The synthesis of O-methyl derivatives of 4-thiopentofuranosides and 2,5-anhydropentoses

Abstract Heating of 2,3,5-tri- O -methyl-4- O - p -tolylsulfonyl- D -ribose diethyl dithioacetal and dibenzyl dithioacetal in aqueous pyridine gave 4- S -ethyl-2,3,5-tri- O -methyl-4-thio- l -lyxose and benzyl 2,3,5-tri- O -methyl-α-1,4-dithio- l -lyxofuranoside, respectively. Similar rearrangements to the 4-thiofuranoside were observed with 2,3,5-tri- O -methyl-4- O - p -tolylsulfonyl- D -xylose and - D -lyxose dibenzyl dithioacetals. 2,3,4-Tri- O -methyl- 5- O - p -tolylsulfonyl- D -ribose or - D -xylose dibenzyl dithioacetal, however, gave upon heating with sodium iodide in acetone 2,5-anhydro-3,4-di- O -methyl- D -ribose or - D -xylose dibenzyl dithioacetal, respectively.

The action of thiols on derivatives of D-xylose

Abstract The action of thiols on 1,2,3,4-tetra- O -acetyl-β- D -xylopyranose gave 2- and 5-alkylthiopentose dithioacetals and alkyl 1-thio- D -xylopyranosides. On treatment with thiols and trifluoroacetic acid- 3- O -acetyl-1,2- O -isopropylidene-α- D -xylofuranose derivatives rapidly formed 4- O -acetyl-2,3-dialkylthio- D -ribose dithioacetal derivatives, which were in turn converted into 4- O -acetel-3- S -benzyl-2,5-epithio-3-thio- D -ribose (or D -arabinose) dithioacetal.

Preparation, X-ray structure and propylaminolysis of 7,7-dichloro-5,7-dihydro -thieno [3,4-b]pyridin-5-one

Refluxing 2-methylpyridine-3-carboxylic acid with thionyl chloride for 6–7 h gave (∼50%) title compound dichlorothienolactone 2 as was confirmed by a X-ray structure analysis. The propylaminolysis of 2 provides a new and convenient access to highly functionalised pyrrolo[3,4-b]pyridine derivatives.

Production of 3- benzoyl-2,1-benzisoxazoles,2-phenyl-4H-3,1-benzoxazin-4-ones, and novel quinolinone derivatives from 2-phenylquinolin-4(1H)-ones and sodium dichloroisocyanurate

A simple synthesis of certain 3-benzoyl-2,1-benzisoxazoles 6 is accomplished via treatment of the corresponding 2-phenylquinolin-4(1H)-one 1 with sodium dichloroisocyanurate 2 in methanolic aq. alkali; the isomeric 2-phenyl-4H-3,1-benzoxazin-4-one 7 is also a product. Under different conditions the same reactants furnish two new types of quinolinone derivative, viz. 3,3-dichloro-2phenylquinolin-4(3H)-one 4 and 2-alkoxy-3,3-dichloro-2,3-dihydro-2-phenylquinolin-4(1H)-one 5, as chief products; the former is an intermediate in the synthesis of products 6 and 7. Some of the chemical properties of the dichloro compounds 4 and 5 are described. Mechanistic pathways and proposals to explain the results and observations are presented.

Novel production of 3-benzoyl-2,1-benzisoxazoles from 2-phenyl-quinolin-4(1H)-ones

2-Phenylquinolin-4(1H)-ones 1a and 1b react with sodium dichloroisocyanurate 2 in methanolic aqueous sodium hydroxide, to afford, after acidification, 3-benzoyl-2,1-benzisoxazoles 3a and 3b(ca. 30%).

Thionyl Chloride-induced Conversion of 1-Ethyl-1,4-dihydro-2-methyl-4-oxoquinoline-3-carboxylic Acids to Highly Functionalised Thieno[3,4-b]quinoline Derivatives

Warming a title acid with SOCl2 gives the corresponding 3,3,9-trichlorothieno[3,4-b]quinolin-1(3H)-one whereas reaction at room temperature leads to the intermediate 3,3-dichloro-4-ethylthieno[3,4-b]quinoline-1(3H),9(4H)-dione product as established from the respective X-ray crystallographic determinations.