The diastereospecific attack of the silyl enol ether on the activated cyclopropyl diester 27 generated the hydrindanone 28 with complete stereocontrol. Thermal decarbomethoxylation of 28 gave the monoester 29, a key intermediate in Heathcock's synthesis, thereby completing a formal total synthesis of (+)-fawcettimine 1. The analogous cyclization of 33, the diastereomer of 27, afforded the diast...

Two strategies for the synthesis of the ATP (adenosine triphosphate) analogue ApppI [1-adenosin-5'-yl 3-(3-methylbut-3-enyl)triphosphoric acid diester] (1) are described. ApppI is an active metabolite of the mevalonate pathway and thus is of major biological significance. Chemically synthezised ApppI was purified by using triethylammonium bicarbonate as the counter ion in ion-pair chromatograph...

Phosphomannosyl residues on acid hydrolases serve as recognition markers which target these enzymes to lysosomes. We have found that the oligosaccharide units of newly synthesized beta-glucuronidase contain phosphate residues in diester linkage between mannose and alpha-linked N-acetylglucosamine residues (Tabas, I., and Kornfeld, S. (1980) J. Biol. Chem. 255, 6633--6639). To obtain larger amou...

Some 3, 5-diacyl or 3,5-diester 1,4-dihydropyridines were oxidized to the corresponding pyridine derivatives using hydrogen peroxide in aqueous ethanol in the presence of potassium bromide and acetic acid as the catalysts. The reaction was carried out in ethanol and products were isolated in high to excellent yields. However, oxidation of 3,5-diacetyl 1,4-dihydropyridines is slower than 3,5-die...

Catalytic promiscuity, an evolutionary concept, also provides a powerful tool for gaining mechanistic insights into enzymatic reactions. Members of the alkaline phosphatase (AP) superfamily are highly amenable to such investigation, with several members having been shown to exhibit promiscuous activity for the cognate reactions of other superfamily members. Previous work has shown that nucleoti...

1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione reacts with ethyl bromoacetate under mild conditions to give 2-(ethoxycarbonylmethyl)-1-phenyl-6H-imidazo[1,5-c]quinazoline-3,5-dione (MEPIQ) and next 2,6-bis(ethoxycarbonylmethyl)-1-phenylimidazo[1,5-c]quinazoline-3,5-dione (BEPIQ). The products were isolated at high yield and identified on the basis of IR, 1H- and 13C-NMR, UV spectroscopy, an...

The chemical composition of plant polyphenols Plantago major L. and lanceolata growing in Uzbekistan was studied. More than 20 compounds, including 7 flavonoids, 9 phenolic acids, 8 hydrolysable tannins, the ages which have been determined using physicochemical methods research isolated from plants. From P. L., along with well-known such as gallic acid, rutin, luteolin, isorhamnetin, hyperoside...

(Carbo)nucleoside derivatives constitute an important class of pharmaceuticals, yet there are only few convergent methods to access new analogues. Here, we report the first synthesis of thymine-, uracil-, and 5-fluorouracil-substituted diester donor-acceptor cyclopropanes and their use in the indium- and tin-catalyzed [3+2] annulations with aldehydes, ketones, and enol ethers. The obtained dies...

1. The metabolism of dehydroretinyl ester has been studied in vitamin-A-deficient white leghorn chicks. Dehydroretinyl ester was metabolized to 3-hydroxyretinol diester, 3-hydroxyanhydroretinol and rehydrovitamin A2 which were isolated from the intestines and livers of chicks. 2. The metabolism of 3-hydroxyretinol diester and 3-hydroxyanhydroretinol, which were immediate metabolites of dehydror...

The phorbol diesters are the most potent inducers of differentiation of the promyelocytic leukemia cell line, HL-60. Soluble phorbol diester receptors from HL-60 cells were obtained from the cytosolic fraction and from the particulate fraction by either divalent ion chelation or detergent extraction. The partially purified soluble phorbol diester receptors required exogenous Ca2+ and phospholip...