Synthesis and X-ray crystal structure study of the hydroxyurea and hydantoin derivatives of L-valine.

The novel hydroxyurea 5 derivative of L-valine was prepared by aminolysis of N-(1-benzotriazolecarbonyl)-L-valine cyclohexanemethylamide 4 with hydroxylamine. The corresponding hydantoin derivative 6 was synthesized by base catalyzed cyclization of the amide 4. The exact stereostructure of hydantoin derivative 6 has been determined by X-ray crystal structure analysis. The chiral atom of the hydantoin ring in 6 has S configuration what is in agreement with its configuration in the starting L-valine. The molecules of 6 are joined into infinite chains by N-H...O intermolecular hydrogen bond. The infinite chains are additionally linked by two C-H...O hydrogen bonds, thus forming two-dimensional network. The hydantoin derivative of L-valine 6 and its L-leucine analogue LH have similar packing arrangements, so they are homostructural.     

Synthesis and radical reaction of 1'-phenylselenonucleosides.

The 1'alpha-phenylselenouridine derivative (4) was successfully synthesized via enolization at the 1'-position of the 3',5'-O-TIPDS-2'-ketouridine (1). After the introduction of a vinylsilyl tether as an intramolecular radical acceptor at the 2'-hydroxy group of 4, its atom-transfer radical cyclization reaction, followed by the treatment with TBAF gave 1'alpha-vinyluridine derivative (10). Using this procedure, 1'alpha-vinyluridine (11) and -cytidine (14) were successfully synthesized.     

Synthesis and properties of a photoaffinity probe for the glucagon receptor in hepatocyte plasma membranes.

The reaction of glucagon with 4-fluoro-3-nitrophenylazide has been shown to afford the photosensitive derivative, Nepsilon-4-azido-2-nitrophenyl-glucagon. The structure and properties of this derivative were established by amino acid analysis, absorption and fluorescence spectroscopy, deamination, Edman degradation and photolysis. This photoaffinity derivative of glucagon has been used to label specifically glucagon binding sites on hepatocyte plasma membranes.     

Synthesis of nucleotide antibiotics having N-acyl phosphoramidate linkages.

This paper reports the synthesis of nucleotide antibiotics having N-acyl phosphoramidate linkages. The key reaction, the construction of the N-acyl phosphoramidate linkage was achieved by the reaction of nucleoside 5'-phosphoramidite derivatives with carboxamide derivatives in the presence of 5-(3,5-dinitrophenyl)-1H-tetrazole as a very effective activator. By use of this activator, Phosmidosine was synthesized by condensation of an appropriately protected 8-oxoadenosine 5'-O-phosphoramidite derivative with an N-protected prolinamide derivative. In the case of Agrocin 84, the two P-N bonds were constructed progressively. The N-acyl phosphoramidate linkage at the 5'-position of the ribose moiety was similarly synthesized. After phosphorylation of the amino group of the adenine moiety, a fully protected Agrocin 84 derivative, which would be converted to Agrocin 84, was successfully synthesized.     

Synthesis of 3'-substituted-2',3'-deoxy-2'-methylidenepyrimidine nucleosides.

2'-deoxy-2'-methylideneuridine derivative 9 was converted into 2',3'-didehydro-2',3'-dideoxy-2'-phenyl-selenomethyl derivative 16, which was treated with NCS and tert-butyl carbamate to afford 3'-amino derivative 18 via a [2,3]-sigmatropic rearrangement. Treatment of 9 with DAST gave a mixture of 2',3'-didehydro-2', 3'-dideoxy-2'-fluoromethyl derivative 19 and 3'-"up"-fluoro-2'-methylidene derivative 20 in a ratio of 1.5 : 1. On the other hand, when 12 was treated with DAST, 19 and 3'-"down"-fluoro-2'-methylidene derivative 21 were obtained in a ratio of 1 : 1.6. These nucleosides were converted into the corresponding cytidine derivatives 4, 6, and 8, respectively. The reaction mechanisms as well as biological activity of these compounds will also be discussed.     

Synthesis and characterization of highly substituted deoxyfluorocellulose acetate.

Deoxyfluorocellulose acetates were prepared from cellulose acetate (CA, degree of substitution by acetyl groups: 2.2 and 1.7) by using diethylaminosulfur trifluoride (DAST) in 1,4-dioxane or diglyme. The maximum degree of substitution of fluorine of the products was approximately 0.60, and depolymerization was not significant during fluorination. The replacement of hydroxyl groups by fluorine atoms occurred exclusively at C-6, as confirmed by carbon-13 NMR spectroscopy. In the presence of pyridine, an N-pyridinium derivative of CA was obtained instead of a deoxyfluoro derivative of cellulose.     

Synthesis of the tBuSATE pronucleotide of AZT by two different synthetic approaches.

A large scale synthesis of the tBuSATE pronucleotide of AZT was required for in vivo studies. A comparative synthesis of this derivative by phosphoramidite and monophosphate approaches is reported.     

Synthesis of novel europium-labeled estradiol derivatives for time-resolved fluoroimmunoassays.

The O-(5-carboxypentyl)-, O-(4-aminobutyl)-, O-(6-aminohexyl)oximes of 2- and 4-formylestradiol as well as the 4-carboxyethylthioether derivative of estradiol were synthesized. These estradiol derivatives were characterized using IR-, 1H-, and 13C NMR spectroscopy. All synthesized estradiol derivatives were labeled with europium chelates. These "tracers" were purified and tested in a competitive time-resolved fluoroimmunoassay with monoclonal antibody (SSI 57-2) raised against the 6-O-(carboxymethyl)oxime-bovine serum albumin derivative of estradiol. All the tested europium-labeled estradiol-4-derivatives were bound by the antibody, whereas tracers linked via position 2 were not recognized by this antibody. It was observed that tracers conjugated via C-4 gave more sensitive standard curves than tracers conjugated via C-6. Especially, the estradiol-4-thioether derivative was found to be highly useful in time-resolved fluoroimmunoassays of estradiol while using this antibody.     

Synthesis of oligonucleotide derivatives containing a bis-pyrene residue in the main chain.

The oligonucleotide having the bis-pyrene residue in the main chain was synthesized. The preparation of the bis-pyrene was started from the conversion of 2,2-bis-(bromomethyl)-1,3-propanediol into the protected bis-amino derivative. The reaction of the bis-amino derivative with 1-pyrenebutyric acid using DCC/HOBT afforded the desired bis-pyrene. This compound was then converted to the protected phosphormidite. The oligonucleotides possessing the bis-pyrene were synthesized by using the amidite. The oligonucleotides having the bis-pyrene residue can bind to DNA sequence in an aqueous solution to give the duplex with comparable thermal stability as that of the unmodified DNA/DNA duplex. The significantly enhanced pyrene-excimer fluorescence was observed upon hybridization of the bis-pyrene modified oligonucleotides with DNA.     

Synthesis and property of alpha-oligodeoxynucleotide phosphorothioate.

Unnatural DNA analog, alpha-2'-deoxy-oligoadenylate phosphorothioate bearing 3'-normal monophosphate moiety was conveniently synthesized through phosphoramidite solid support method. The starting material of the DNA analog, alpha-2'-deoxyadenosine, was prepared in a stereospecific manner by the coupling reaction between activated nucleobase and 1-chloro-2-deoxyribose derivative.     

Synthesis of capsular polysaccharide of Streptococcus pneumoniae type 14. 3. Synthesis of a monomer for polycondensation

Synthesis of a tritylated tetrasaccharide 1,2-O-(1-cyano) ethylidene derivative is described by glycosylation of 3,6-di-O-benzoyl-4-O-(2,4,6-tri-O-benzoyl-beta- D-galactopyranosyl)-1,2-O-[1-(exo-cyano)ethylidene]-alpha-D- glucopyranose with 6-O-acetyl-3-O-benzoyl-4-O-(2,3,4,6-tetra-O-benzoyl-beta- D-galactopyranosyl)-2-deozy-2-phthalimido-D-glucopyranosyl. bromide followed by selective deacetylation and tritylation.     

Synthesis and biological activity of the mono- and di-galactosyl-vespulakinin 1 analogues.

Syntheses are described of some mono- and di-glycosylated analogues of vespulakinin 1. The solid phase procedure, based on the Fmoc chemistry, was used to prepare (Gal alpha)Thr3-vespulakinin 1, (Gal beta)Thr3-vespulakinin 1 and the di-glycosylated analogue ((Gal alpha)Thr3, (Gal alpha)Thr4-vespulakinin 1. The beta-glycosylated derivative was also prepared by the continuous flow variant of the Fmoc polyamide method. The synthesized glycopeptides were purified and characterized by amino acid analysis, optical rotation, analytical HPLC, 1H- and 13C-NMR and FAB-MS. Preliminary pharmacological experiments showed that the carbohydrate-free vespulakinin 1 is less active than bradykinin (about 0.3 times on a molar basis) when tested by guinea pig rectum contraction, and the two monoglycosylated analogues are equiactive (about 0.9 times the bradykinin activity). The most active derivative, the (Gal alpha)Thr3, (Gal alpha)Thr4-vespulakinin 1 analogue, was about 2.5 times as active as bradykinin.     

Porphyrin-linked oligonucleotides. Synthesis and sequence-specific modification of ssDNA

Oligonucleotide derivatives bearing hemin and deuterohemin groups were synthesized. The derivatives efficiently react with the complementary nucleotide sequence in ssDNA forming covalent adducts and piperidine-labile sites. In the case of the deuterohemin derivative, some direct cleavage of the target DNA occurs.     

A Reinvestigation of the Synthesis of 4-Thio-Pentofuranosides for Further Nucleosidic Synthesis

Abstract

We demonstrate that the procedure of Huang and Hui⁽⁴⁾, applied to the D-ribose and involving Ph₃P/I₂/Imidazole reagent system do not lead to the desired 4-thio-D-ribofuranoside derivative but gives its diastereoisomer 4-thio-L-lyxofuranoside derivative 4      

Synthesis of coenzymically active soluble and insoluble macromolecularized NAD+ derivatives.

Alkylation at N-1 of the NAD+ adenine ring with 3,4-epoxybutanoic acid, followed by chemical reduction to the alkali-stable NADH form and alkaline Dimroth rearrangement, gave the NADH derivative alkylated at the exocyclic adenine amino group. Enzymic reoxidation of the latter derivative gave nicotinamide-6-(2-hydroxy-3-carboxypropylamino)purine dinucleotide, a functionalized NAD+ analogue carrying an omega-carboxyalkyl side-chain at the exocyclic adenine amino group. Carbodiimide coupling of the latter derivative to high-molecular-weight water-soluble (polyethyleneimine, polylysine) and insoluble (aminohexyl-Sepharose) polymers gave the corresponding macromolecularized NAD+ analogues. These derivatives have been shown to be enzymically reducible. The polyethyleneimine and polylysine analogues showed a substantial degree of efficiency relative to free NAD+ with rabbit muscle lactate dehydrogenase (60 and 25% respectively) but a lower one with yeast alcohol dehydrogenase and Bacillus subtilis alanine dehydrogenase (2-7%). The polyethyleneimine derivative entrapped in cellulose triacetate fibres together with the lactate dehydrogenase was operationally stable during repetitive use.     

Aminonucleosides and their derivatives. IV. Synthesis of the 3'-amino-3'-deoxynucleoside 5'-phosphates.

A new procedure has been developed for the synthesis of 3'-amino-3'-deoxyribonucleosides of adenine, cytosine and uracil by condensing the trimethylsilylated bases with peracylated 3-azido-3-deoxyribose derivative. The azido group could subsequently be reduced to amino. The 5'-phosphates of these nucleosides have been prepared and the analogues have been tested for their ability to stimulate the ribosome-catalyzed reaction of 3'(2')-O-(N-formylmethionyl) adenosine 5'-phosphate with phenylalanyl-tRNA.     

Synthesis of sulfated bioactive peptides using immobilized arylsulfotransferase from Eubacterium sp.

Summary An arylsulfotransferase from Eubacterium sp. was immobilized on agarose gels by multipoint covalent attachment. The yield of immobilization was 80% with an activity of 11 UA/ml of derivative. After 19 days of incubation, the loss of activity of the derivative was 36%. The immobilized preparation was used to transfer selectively a sulfate group from p-nitrophenolsulfate to selected tyrosine containing biologically active peptides in 92–99% of yield.     

Synthesis of 8-C-glucosylflavones

The syntheses of orientin, parkinsonin A, isoswertiajaponin, and parkinsonin B, which are 8-C-beta-D-glucopyranosyl-3',4',5,7-tetrahydroxyflavone, 5-methyl orientin, 7-methyl orientin, and 5,7-dimethyl orientin, respectively, are reported herein. The C-glucosyl phloroacetophenone derivatives were obtained via a regio- and stereoselective O-->C glycosyl rearrangement. Aldol condensation of the C-glucosyl phloroacetophenone derivatives with 3,4-bisbenzyloxybenzaldehyde afforded the corresponding C-glucosylchalcones. Construction of the flavone system by reaction with I(2)-Me(2)SO, followed by the elimination of the 5-benzyl protecting group in the flavone structure, yielded an orientin derivative and a isoswertiajaponin derivative. Methylation of the orientin derivatives with dimethyl sulfate afforded the parkinsonin A derivative, the isoswertiajaponin derivative, and the parkinsonin B derivative. Finally, hydrogenolysis of these C-glucosylflavone derivatives led to the four 8-C-glucosylflavones. The NMR spectra of these C-glucosylflavones showed a duplication of signals corresponding to a major rotamer, along with a minor one. Based on NOESY experiments in Me(2)SO at ambient temperature, they adopted conformations in which the H-2"and H-4" protons in the glucose moiety were oriented toward the B-ring in the flavone structure.     

Synthesis of a Fluorobenzoxazine Derivative and Its Analogues

Syntheses of a fluorobenzoxazine derivative, fluorobenzothiazine derivative and fluoroquinoxaline derivative are described. These compounds were synthesized by reductive cyclization of the corresponding fluorodinitrobenzene derivatives. The fluorobenzoxazine derivative and its analogues are useful intermediates for agro-chemicals.     

Synthesis of 4'-ethynyl-purine nucleosides possessing anti-HIV activity.

Searching for more effective anti-HIV agents, we have prepared 4'-ethynyl-purine nucleosides. They were derived in several steps from 4-C-triethylsilylethynyl ribose, which was used as an intermediate in the synthesis of pyrimidine nucleosides. The adenine derivative exhibited significant anti-HIV activity and favorable cytotoxicity profile in vitro.