A simple synthesis of choline alkyl phosphates

Alkyl (2-dimethylamino)ethyl methyl phosphates are prepared and isomerize smoothly to the corresponding alkyl choline phosphates.     

Nature and Thermal Behavior of Precipitated Calcium-Magnesium Phosphates

A group of crystalline and amorphous calcium-magnesium phosphates were prepared by exchange in solution of sodium orthophosphate and calcium and magnesium chlorides at pH 8-12. The behavior of the phosphates on heating to 1000°C was studied.     

Esters phosphoriques,phosphonates et oxydes de phosphine dérivés de sucres. Communication préliminaire

Some sugar phosphates, phosphonates and phosphine oxides, Preliminary communication Some new phosphates of 1, 2-O-isopropylidene-α-D-ribofuranose have been prepared. Reactions of 3-C-cyanomethylidene-3-deoxy-1, 2-O-isopropylidene-5-O-trityl-α-D -erythro-pentofuranose (9) have been studied. On treatment with phosphorus nucleophiles, 9 led to phosphorus bearing branched-chain sugar derivatives. Branched-chain cyanosugars as 15 and 16 prepared by cis-vic-dihydroxylation of 9 constitute interesting potential precursors of new types of cyclic sugar phosphates.     

Synthesis and use of glycosyl phosphates as glycosyl donors

Differentially protected glycosyl phosphates prepared by a straightforward synthesis from glycal precursors are used as powerful glycosyl donors. Activation of beta-glycosyl phosphates by TMSOTf at -78 degrees C achieves the selective formation of beta-glycosidic linkages in excellent yields with complete stereoselectivity. Reaction with thiols results in the conversion of glycosyl phosphates into thioglycosides in nearly quantitative yield. An orthogonal coupling strategy using glycosyl phosphate donors and thioethyl glycoside acceptors allows for the rapid synthesis of a trisaccharide.     

IMPROVED SYNTHESIS OF CYANOHYDRIN PHOSPHATES AND ITS REACTION MECHANISM

Cyanohydrin phosphates 2a–2c were prepared in high yield from ketones (or aldehyde), diethyl phosphorochloridate, and sodium cyanide by using acetonitrile as solvent. GC analysis proved that the two reactions of cyanohydrin sodium with diethyl phosphorochloridate and with diethyl phosphorocyanidate resulted in the formation of cyanohydrin phosphates.     

磷酸锆催化甘油气相脱水制备丙烯醛

以沉淀法、水热合成法和浸渍法制备了磷酸锆催化剂,通过X射线衍射、热重分析、氮气物理吸附、红外光谱和Hammett指示剂法对催化剂进行了表征,并将该催化剂用于甘油气相脱水反应.研究表明,由沉淀法得到的磷酸锆经过400℃焙烧后能达到最佳催化活性,在温和条件下,甘油可完全转化,丙烯醛选择性为81%,反应24h内催化剂失活不明显.不同方法制备的磷酸锆其结构和表面酸性显著不同,催化剂表面酸性对催化剂活性、丙烯醛选择性和催化剂的寿命均有较大影响.     

General approach to allenes through copper-catalyzed γ-selective and stereospecific coupling between propargylic phosphates and alkylboranes

Copper-catalyzed γ-selective coupling between propargylic phosphates and alkylboron compounds (alkyl-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) affords multisubstituted allenes with various functional groups. The reaction of enantioenriched propargylic phosphates to give axially chiral allenes proceeds with excellent point-to-axial chirality transfer with 1,3-anti stereochemistry.     

应用固-液相转移催1化方法合成肌醇磷酸脂

固-液相转移催化方法已成功地应用于各种肌醇磷酸脂的合成.在固- 液相转移催化条件下,肌醇衍生物O-烷基化的选择性得到了有效的改进;而在固- 液相转移催化条件下的atheron-todd反应,为肌醇衍生物的磷酰化提供了一个良好的新方法.     

High surface area Pd, Pt and Ni ion-exchanged Zr, Ti and Sn(IV) phosphates and their application to selective heterogeneous catalytic hydrogenation of alkenes

Amorphous acidic metal(IV) phosphates of zirconium, titanium and tin have been prepared and hydrogen-exchanged for bivalent Pd, Pt and Ni. These bivalent metals were returned to the zero valent state by reducing them with either hydrogen at 400 °C or with sodium tetrahydroborate at room temperature. The resulting Pd⁰, Pt⁰ and Ni⁰ phosphates were investigated as selective catalysts for heterogeneous hydrogenation of alkenes in solution at normal temperatures and pressures and, for Ni, also in the vapour phase. Quantitative studies on rates of hydrogenation are discussed. The usual methods for preparing metal(IV) phosphates give either crystalline or amorphous solids having low specific surfaces areas. A method has been developed, by which metal(IV) phosphates having large surface areas (lsa) may be prepared easily. These lsa supports take up large amounts of transition metal cations by simple exchange. The enhanced incorporation of Pd, Pt or Ni and increases in surface areas of the phosphate supports have provided some active, selective catalysts. Pd/Ti phosphates were the most active and compared well with commercial Pd on carbon. Ni/Ti phosphate is a very selective catalyst for vapour phase hydrogenation of alkenes and, at slightly higher temperatures, it is an efficient hydrocarbon cracking catalyst.     

NH3 TPD study and thermal behaviour of vanadium-exchanged titanium phosphates as catalysts

The ion exchange technique was employed for the preparation of VO²⁺ modified titanium phosphates as catalysts for the selective reduction of NO with NH₃. The samples were prepared by contacting with a vanadyl sulphate solution different precursor materials, amorphous, crystalline or sodium half exchanged titanium phosphate. The vanadium contents of modified phosphates were in the range 0.08–2.3 wt%. XRD and thermal analysis TG/DTA showed that vanadium loading does not cause structural modification in hydrogen titanium phosphate. A vanadyl containing phase was obtained when half sodium titanium phosphate was employed. The NH₃ TPD measurements indicated the presence of a wide distribution of NH₃ adsorbing sites with medium-high strength. Catalytic activity measurements were performed under dilute conditions. It was found that the presence of vanadium even in low amounts strongly promote the catalytic activity.     

Synthesis of Some Specifically Deoxygenated D-Hexopyranosyl Phosphates

Abstract

A number of diphenyl α-glucopyranosyl and xylopyranosyl phosphates (4, 7, 11. 15, 19, and 25) were prepared from their respective glycosyl chlorides by reaction with silver diphenyl phosphate. These sugar phosphates are of interest as enzyme substrates in deoxy sugar biosynthesis.     

Syntheses and Bioactivity of o- or p-Trifluoromethylphenyl Phosphates

o- and p-Trifluoromethylphenyl phosphates designed as mechanism-based phosphotyrosine phosphatase inactivators have been prepared. Some of them show herbicidal activities.     

Benzylic manganese halides, sulfonates, and phosphates: preparation, coupling reactions, and applications in organic synthesis

The use of highly active manganese, prepared by the Rieke method, for the direct preparation of benzylic manganese reagents was investigated. The oxidative addition of the highly active manganese (Mn) to benzylic halides was easily completed under mild conditions. More importantly, benzylic manganese sulfonates and phosphates were prepared by direct oxidative addition of Mn to the carbon-oxygen bonds of benzylic sulfonates and phosphates. The resulting benzylic manganese reagents were found to undergo cross-coupling reactions with a variety of electrophiles. The majority of these reactions were carried out in the absence of any transition metal catalyst under mild conditions. This approach also provided a facile synthetic route to the preparation of resorcinolic lipids.     

Synthesis of phosphoric esters of bridgehead alcohols

Dibenzylphosphates of 1-adamantanol and kemantane, 1-adamantyl phosphate, and a series of diphenyl phosphates of bridgehead alcohols have been prepared.     

Solid-phase oligosaccharide synthesis: preparation of complex structures using a novel linker and different glycosylating agents

[formula: see text] A beta-(1-->4)-linked trisaccharide was prepared in 53% yield on a polymer support using glycosyl phosphates and released by cross-metathesis of a novel linker to reveal the anomeric n-pentenyl glycoside. Heptasaccharide 33 was prepared in 9% yield in 14 steps.     

The 1,3-migration of phosphorus from oxygen to carbon: A new synthesis of β-ketophosphonates from enol phosphates

Enol phosphates, readily prepared from ketone enolates and dialkyl phosphorochloridate, can be converted to the analogous β-ketophosphonates by treatment with strong base.     

Facile Synthesis of 1-Alkynylphosphonates

1-Alkynylphosphonates 4 are prepared by the in situ β-elimination of enol phosphates 3, which are readily generated by the reaction of sodium enolate of 2-oxophosphonate with diethyl chlorophosphate.     

Stereoselective synthesis of 3,6-disubstituted-3,6-dihydropyridin-2-ones as potential diketopiperazine mimetics using organocopper-mediated anti-SN2' reactions and their use in the preparation of low-molecule CXCR4 antagonists

Organocopper-mediated anti-SN2' reactions of gamma-phosphoryloxy-alpha,beta-unsaturated-delta-lactams were used to prepare highly functionalized diketopiperazine mimetics. The substrate phosphates 24, 32, and 47 were prepared from alpha-amino acid-derived allylic alcohols 10 by a sequence of reactions that included ring-closing metathesis. In the reactions of phosphates with organocopper reagents, the addition of LiCl dramatically improved anti-SN2' selectivity, indicating that an organocopper cluster containing lithium chloride plays an important role in the determination of regioselectivity. This reaction system was applied to the preparation of novel low molecular weight CXCR4-chemokine receptor antagonists.     

Iron phosphate microflowers as peroxidase mimic and superoxide dismutase mimic for biocatalysis and biosensing

Novel iron phosphates microflowers which show SOD-like and peroxidase-like mimic activities were prepared, suggesting potential applications as a biocatalyst and a biosensor for H(2)O(2).     

Sequential asymmetric homoallenylation of primary amines with a palladium catalyst

Optically active bis(homoallenyl)amines bearing two chiral axes with the same sense of axial chirality were prepared by a one-pot, palladium-catalyzed sequential homoallenylation of primary amines with 2,3-allenyl phosphates.