Tatsuo Oshikawa

Utilization of dendritic framework as a multivalent ligand: a functionalized gadolinium(III) carrier with glycoside cluster periphery

Abstract A new type of designed and functionalized ligand for a lanthanide ion based on dendritic architecture was synthesized. The dendrimers, which contain four and twelve glucose moieties on the molecular surfaces, were readily synthesized with good yields in every step. The NMR and GPC analyses precisely demonstrated successful constructions of the dendritic structures, while the formations of gadolinium chelates were deduced on the basis of HPLC study.

Synthesis and photoluminescence study of anthracene based dendrimer and dendron

A new type of polyaromatic dendrimer composed of six anthracene groups was synthesized, which showed a monomeric fluorescence feature with a diminished quantum yield due to intramolecular self-quenching processes in the dendritic framework.

An efficient approach towards the stereospecific synthesis of epoxides from phospholene oxides

A novel method has been developed for stereospecific conversion of 2-phospholene 1-oxides into their corresponding 2,3-epoxides in high yields using sodium peroxide as a reagent.

Novel Synthesis and Structures of Amines and Triazole-Derived Glycoside and Nucleoside Derivatives of Phosphanyl Sugar Analogs

ABSTRACT 3-Methyl-1-phenyl-2-phospholene and 1-phenyl-2-phospholene 1-oxides were converted into 2-bromo-3-hydroxy-3-methyl-1-phenylphospholane and 2-bromo-3-hydroxy-1-phenylphospholane 1-oxide (1-bromo-1,3,4-trideoxy-1,4-C-[(R, S)-phenylphosphinylidene]-glycero-tetrofuranose) by the action of bromine in aqueous medium. The bromo substituent of the phospholane was substituted by treatment with amines or an azide anion to afford novel glycoside derivatives of phosphanyl sugar analogs such as 2-amino-3-hydroxy-1-phenylphospholane (3,4-dideoxy-1,4-C-[(R, S)-phenylphosphinylidene]-glycero-tetrofuranosylamine) and 2-azido-3-hydroxy-3-methyl-1-phenylphospholane 1-oxides with retention of the configuration. The 1,3-dipolar cycloaddition of the 2-azido derivative of the phospholane with alkynes gave 3-hydroxy-3-methyl-1-phenyl-2-(triazol-1′-y1)phospholane 1-oxides as a novel triazole-derived nucleoside of phosphanyl sugar analogs. The structure of the glycoside and nucleoside derivatives of the phosphanyl sugar a...

An efficient synthesis of novel deoxy phospha sugar pyrimidine nucleosides

Abstract An efficient method is described in the synthesis of several novel deoxy phospha sugar pyrimidine nucleosides in racemic form, analogs of normal sugar nucleosides, in high yields by treatment of (±)-2-aminophospholane 1-oxide with several, α-cyano-, -acetyl-, -ethoxycarbonyl-β-ethoxy-N-ethoxycarbonylacrylamides.

Synthesis of novel deoxy λ5 phospha sugar nucleosides: 1,3-dipolar cycloaddition of an azidophospholane with alkynes

Several novel phospha sugar nucleosides, analogs of normal sugar nucleosides, were synthesized from a phospholene 1-oxide derivative. Bromination of a phospholene precursor in aqueous organic medium gave regio diastereomers, the threo and erythro bromohydrins 3 (1-bromo-1,3,4-trideoxy-1,4-C-[(R,S)-phenylphosphinylidene]-glycero-tetrofuranose). Further substitution of the threo isomer 3a with sodium azide led to its corresponding azidophospholane 4 (1-azido-1,3,4-trideoxy-2-methyl-1,4-C-[(R)-phenylphosphinylidene]-beta-D-glycero-tetrofuranose). 1,3-Dipolar cycloaddition of 4 with various electron-deficient and electron-rich alkynes afforded triazole derivatives that are nucleoside analogues. The strong electron-withdrawing phosphoryl group in the hemiacetal ring exerted no effect over reaction regioselectivity of the 1,3-dipolar cycloaddition, but steric effects of the alkynes played a vital role on the selectivity, since the regioisomer ratios and the rates and yields of cycloadducts changed as the bulkiness of the substituents on the acetylene changes. Structures of all compounds were unequivocally confirmed by 1H, 13C, and 31P NMR and mass spectral studies. Single crystal X-ray crystallographic analysis of some derivatives allowed determination of configuration of the phospha sugar nucleosides.

Structural and conformational properties of (Z)-?-(1-naphthyl)- dehydroalanine residue

To understand how chemical structure of beta-substituted alpha, beta-dehydroalanine (particularly size and pi conjugation of beta substituent) affects conformational property, x-ray crystallographic analysis was performed on Boc-Ala-Delta(Z) Nap-Val-OMe [Boc: t-butoxycarbonyl; Delta(Z) Nap: (Z)-beta-(1-naphthyl)dehydroalanine; OMe: methoxy] having the naphthyl group as a bulky beta substituent. Single crystals were grown by slow evaporation from an ethanol solution in the triclinic space group P1 with a = 9.528 (3) A, b = 12.410(4) A, c = 5.975(2) A, alpha = 96.77(3) degrees, beta = 102. 81(2) degrees, gamma = 88.74(3) degrees, V = 684.1(4) A3, and Z = 1. Phase determination was carried out by a direct method (SHELEXS), and the final structure was refined to R = 8.1% and R(w) = 9.0% for 1964 observed reflections. The bond lengths and bond angles of the Delta(Z)Nap residue, characterized by a sp(2) hybridized C(alpha) atom, did not differ from those of other dehydroresidues such as Delta(Z) Phe, Delta(Z) Leu, and DeltaVal essentially. The peptide backbone took a type II beta-turn conformation involving an intramolecular hydrogen bond between CO(Boc) and NH(Val), similar to di- or tripeptides containing a Delta(Z) Phe or Delta(Z) Leu residue in the second positions. Here the naphthyl group was found to be nonplanar [chi(2) = 55(1) degrees ] relative to the C(alpha)==C(beta)==C(gamma) plane. The nonplanarity was supported by conformational energy calculation. The molecular packing was stabilized by two kinds of intermolecular hydrogen bonds and van der Waals interactions. Naphthyl groups were arranged in a partially overlapped face-to-face orientation with a center-to-center distance of 5.97 A. For additional information, peptide Boc-(Ala-Delta(Z) Nap-Leu)(2)-OMe was synthesized and its solution conformation was investigated by (1)H-NMR spectroscopy. The hexapeptide showed the tendency to form a 3(10)-helical conformation in solution essentially. Conformational properties of Delta(Z) Nap residue, characterized by a type II beta-turn and 3(10)-helix, were supported by a conformational energy contour map of the Delta(Z)Nap residue.

Novel Synthesis and Structure of Phosphanyl Sugar Derivatives 1

Abstract Some phosphanyl sugar derivatives, which are analogs of sugars having a phosphorus atom in place of the ring oxygen, were synthesized from 2- and 3-phospholenes as starting materials. Catalytic cis-dihydroxylation of 2-phospholene or 3-phospholene 1-oxide derivatives with osmium(VIII) oxide in the presence of a cooxidant afforded 3-deoxy- or 1-deoxy-tetrofuranose-type phosphanyl sugar derivatives, respectively. cis- Dihydroxylation of 4-acyloxy-2-phospholene 1-oxide derivatives gave tetrofuranose type phosphanyl sugar derivatives. Some of these derivatives of phosphanyl sugars were subjected to structural analyses using 1H NMR and X-ray crystallography. 1. Presented at the XVIIIth Inlernational Carbohydrate Symposium, Milan, Italy, July 21-26, 1996.

Preparation And Characterization Of Phospholanes And Phospha Sugars As Novel Anti-Cancer Agents

Diastereo isomeric erythro and threo forms of 2,3-epoxy-l-phenylphospholane 1-oxides were synthesized from threo and erythro forms of 2-bromo-3-hydroxy-l-phenylphospholane 1-oxides being prepared from l-phenyl-2-phospholene 1-oxide. Alternatively, the epoxides were also prepared by the epoxidation of the 2-phospholene with peroxides such as sodium peroxide and hydrogen peroxide. The reactivity and regioselectivity for the reaction of erythro and threo forms of the 2,3-epoxides with nucleophiles were investigated by using amines, and the reaction afforded 2-amino-3-hydroxy-l-phenylphospholane 1-oxides, which correspond to phospha sugar N-glycosides. 2,3-Dibromo-3-methyl-l-phenylphospholane 1-oxides were first prepared from 3-methyl-l-phenyl-2-phospholene 1-oxide. The prepared phospholanes or phospha sugars were biologically qualified by ΜΤΓ (3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide) in vitro method to find that some of these phosphorus heterocycles or phospha sugars have quite efficient anti-cancer activity for leukemia cells in manners of (i) wide spectra, (ii) high activities, and (iii) high specificities.

Synthesis of 5-deoxy-3-O-methyl-5-C-(phenylphosphinyl)-l-idopyranose

Synthese a partir de didesoxy-5,6 O-isopropylidene-1,2 O-methyl-3 nitro-6 α-D-xylo-hexeno-5furanose et de phenylphosphine