SYNTHESIS OF CHIRAL THIOCARBAMOYLPHOSPHINES DERIVED FROM AMINO ACIDS1

Abstract

The methylester hydrochlorides of the (S)-amino acids L-alanine (la), L-phenylalanine (1b), L-valine (1c) and L-lysine (1d) were converted to the corresponding isothiocyanates 2a-d by thiophosgenation. 2a-d react with secondary phosphines and phosphine oxides to give the thiocarbamoylphosphines 3a-d and P-oxides 4a, b.     

ONE-POT OXIDATION OF AZOMETHINE COMPOUNDS INTO ARENECARBOXYLIC ACIDS

Aromatic azomethine compounds, such as aldazines 1, aldoximes 7 and tosylhydrazones 8 oxidized with 30% hydrogen peroxide in the presence of poly(bis-1,2-phenylene) diselenide (6) as catalyst produce arenecarboxylic acids 2 mostly in high to excellent yields. The presented one-pot procedure has a synthetic value.     

HYDROLYTIC DESULFONATION OF CERTAIN AMINOBENZENESULFONIC ACIDS

Abstract

Hydrolytic desulfonation, a general procedure for the replacement of an aromatic sulfonic group by a proton, has wide scientific and commercial utility:¹     

NEW SYNTHETIC ROUTE TO DIALKYLPHOSPHINIC ACIDS

Abstract

The dialkylphosphinic acids, 5a-5e, can be obtained by reacting bis(trimethylsiloxy)phosphine with the highly reactive alkyl halides, 2a-2e, in the presence of chlorotrimethylsilane and triethylamine, followed by ethanolysis of the resulting trimethylsilyl dialkylphosphinates, 4a-4e.     

HYDROCHLORINATION OF 2,3-ACETYLENIC ACIDS WITH THIONYL CHLORIDE IN DIMETHYLFORMAMIDE

ABSTRACT

The reaction of 2,3-acetylenic acids (1a–d) with thionyl chloride in DMF under mild conditions gave E,Z-3-chloro-2-alkenoic acids (2a–d) or esters (3a–d) depending on treating the reaction mixture with either water or alcohols.     

A CONVENIENT SYNTHESIS OF 2-ALKYL-8-QUINOLINE CARBOXYLIC ACIDS

ABSTRACT

2-Methyl-8-quinoline carboxylic acid 1 was readily synthesized by the improved Doebner–Miller reaction using anthranilic acid and crotonaldehyde in a two phase system containing 5 mol% PTC. By alkylation of methyl group in 1, other 2-alkyl-8-quinoline carboxylic acids (2a and 2b) have been easily prepared.     

CONVENIENT SYNTHETIC METHODS FOR THE PREPARATION OF N-FLUOROALKYLHYDROXAMIC ACIDS

ABSTRACT

Polyhydroxamate chelators containing fluoro substituents are of interest as potential extractants for actinides in separations involving supercritical carbon dioxide. In this context, we have developed three new reagents 1, 2, and 3, that allow the efficient incorporation of an N-fluoroalkyl hydroxamate moiety onto a variety of substrates using acylation, alkylation, and Michael addition strategies.     

STUDIES ON ORGANOPHOSPHORUS COMPOUNDS PART IX.1 THE ACTION OF Di-, TRIALKYL PHOSPHITES AND THIOL ACIDS ON SOME ENAMINOLACTONES

Abstract

Di-, and trimethylphosphites react with enaminolactone, 4, only in methanol to give N-benzoyl-3-phenyl-3-phosphonoalanine-trimethylester (7) in good yields. Diphenylphosphinodithioic acid also reacts with 4 to give N-benzoyl-3-phenylcysteine-methyl ester-diphenylphosphinodithioate (9). A mechanism is proposed to account for the formation of 7. Compatible analytical and spectroscopic results were obtained for the new compounds.     

PREPARATION OF METHYL ESTER DERIVATIVES OF AMINO ACIDS BEARING HYDROLYSABLE N-PROTECTION

ABSTRACT

A convenient method for the esterification of amino acids bearing labile N-substituents is described. Three compounds, 2(a–c), have been synthesised with retention of an N-trifluoroacetamide or an enamine group.     

A DIRECT ROUTE TO ORTHO-HYDROXY PHENYL DITHIOPHOSPHINIC ACIDS

Abstract

Through a direct and selective deprotection of 1 (R=methyl) with boron tribromide substituted o-hydroxy-dithiophosphinic acid 1 was prepared under mild conditions in excellent yield.     

MIXED ANHYDRIDES OF DIALKYLPHOSPHINOUS ACIDS AND DIALKYL HYDROGEN PHOSPHITES,AND THE ISOMERIC MONOXIDES

Abstract

The three isomers possible for oxidized 1,1-dialkyl-2,2-dialkoxydiphosphines, R₂(O)P–P(OR')₂ 1, R₂P–O–P(OR')₂ 2, and R₂P–P(O)(OR')₂ 3, have been synthesized. Irreversible transformations of 1 to 2 and 2 to 3 have been found and the rearrangement patterns, the role of electrophilic and nucleophilic catalysts are discussed. The fact that 3 is more stable than 1 is attributed to higher donor activity of the ligands attached to the four-coordinate phosphorus in 3. Acid chlorides have been shown to attack the phosphorus atom of ambident anions of trivalent phosphorus acids (the products are 1 and 3) whereas the acids proper react with the acid halides at the oxygen atom, to give 2.     

AN IMPROVED SYNTHESIS OF FERROCENYLVINYLPYRIDINE DERIVATIVES USING LEWIS ACIDS/SiO2 SYSTEMS

ABSTRACT

Five ferrocene derivatives with pendant arms containing a terminal 4-pyridyl binding site were prepared in satisfactory yields by reaction of acylferrocene with 4-methylpyridine and followed by dehydration in dry state using p-toluensulfonic acids/SiO₂ systems. The method is very convenient and economical.     

SYNTHESIS OF CYCLIC CONSTRAINED β-OXO-SUBSTITUTED α-AMINO ACIDS

ABSTRACT

Ru(II)-catalyzed RCM reaction with a 5,5-diene of (2R)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine provided a spiroannulated cyclohexenone as substrate for conjugate additions of organocuprates. Acid hydrolysis gave β-oxo-substituted α-amino acids. Assignments of configurations are based on single crystal X-ray analyses.     

OLEFIN SYNTHESIS VIA THE LITHIUM DERIVATIVES OF THE N,N,N,N′-TETRAMETHYLDIAMIDES OF ARYLMETHANEPHOSPHONIC ACIDS. 2. SYNTHESIS OF SOME (Z)-ORTHO-AND PARA-SUBSTITUTED STILBENES

Abstract

The reaction of the lithium derivatives of N,N,N′,N′-tetramethyldiamides of arylmethanephosphonic acids (1-Li) with ortho- and para-substituted benzaldehydes 2 is studied. Reaction conditions are found for erythro-stereoselective addition of 1 to 2 with high diastereomeric purity (95–99%) of the erythro adducts 3, 4 (yields 35–72%). By thermolysis of the adducts in neutral medium the corresponding (Z)-ortho and para-substituted stilbenes 5, 6 are obtained. Some factors causing the predominant formation of the erythro adducts 3, 4, as well as the influence of the ortho-substituents on the equilibrium threo-3, 4 ? erythro-3, 4 are discussed.     

OLEFIN SYNTHESIS USING LITHIUM DERIVATIVES OF N,N,N',N'-TETRAMETHYLDIAMIDES OF ARYLMETHANEPHOSPHONIC ACIDS

Abstract

The reaction of lithium derivatives of N,N,N',N'-tetramethyldiamides of arylmethanephosphonic acids (1-Li) with aldehydes 2 is studied. It is found that under certain reaction conditions (THF, 5 hrs at -70°C and then allowing to warm to room temperature) the aldol stage of the reaction is highly stereoselective, only erythro adducts (2-hydroxyphosphonamides) 3, 4 being formed in 47–75% yields. By heating of 3 and 4 in neutral medium the corresponding (Z)-olefins 5, 6 are obtained (yields 64–74%). It is established that an acid catalyzed olefination of 2-hydroxyphosphonamides is also possible, but the reaction is not stereospecific.     

SUBSTITUENT DIRECTIVE EFFECTS IN THE FRIEDEL-CRAFTS SYNTHESIS OF SUBSTITUTED PHENOXAPHOSPHINIC ACIDS

Abstract

Although meta-substituents on diphenyl ethers block attack at the para-position in the reaction with phosphorus trichloride and aluminium chloride, in some cases phosphorylation occurs in the even sterically more shielded ortho-position, leading to mixtures of isomeric phenoxaphosphinic acids. This effect and the obtained ratios of isomers can be explained by different substituent directive effects in a two step reaction mechanism.     

NEW RADIOHALOGENATED ALKENYL TELLURIUM FATTY ACIDS

Abstract

Radiolabeled long-chain fatty acids have diagnostic value as radiopharmaceutical tools in myocardial imaging. Some applications of these fatty acids are limited due to their natural metabolic degradation in vivo with subsequent washout of the radioactivity from the myocardium. The identification of structural features which will increase the myocardial residence time without decreasing the heart uptake of long-chain fatty acids is of interest. Fatty acids containing the tellurium heteroatom were the first modified fatty acids developed and show unique prolonged myocardial retention and low blood levels. Our detailed studies with radioiodinated vinyliodide substituted tellurium fatty acids demonstrate that heart uptake is a function of the tellurium position. New techniques of tellurium and organoborane chemistry have been developed for the synthesis of a variety of radioiodinated iodoalkenyl tellurium fatty acids.     

DITHIOPHOSPHORIC ACIDS AND TETRAPHOSPHORUS DECASULFIDE IN THE SYNTHESIS OF BORON DITHIOPHOSPHATES

Abstract

The reactions of O,O-dialkyl dithiophosphoric acids with triisobutyl borate, ammonium O,O-diisobutyl dithiophosphate with fluorodiisobutyl borate, and tetraphosphorus decasulfide with triisobutyl borate were studied. On the basis of these studies, new boron derivatives of dithiophosphoric acids were obtained. Low frequency ultrasonic irradiation (22 kHz, power 130 W) leads to reduction in reaction temperature and time in the reactions studied.     

CARBODIIMIDE-MEDIATED ESTERIFICATIONS AND CONDENSATIONS OF PHOSPHORIC ACIDS DISSOLVED IN VARIOUS ALCOHOLS

Abstract

Carbodiimide-mediated phosphorylations carried out with ortho-, pyro-, trimeta-, tetrameta-, and long-chain polyphosphoric acids dissolved in various alcohols, with and without an excess of tri-n-butylamine at 27° were found to consist of complicated reaction sequences involving various phosphoric acids, then esters and complexes formed between the carbodiimide and these acids or esters. In the case of the condensation of orthophosphoric acid, the process of stepwise esterification is seen to compete with the process of condensation to form condensed phosphoric acids and their esters. In general, esterification as opposed to condensation is promoted by (a) increased acidity, (b) smaller size, and (c) increased concentration of the alcohol, as well as by (d) increased concentration of dissociable protons in the solution. ³¹P chemical-shift data are given for ortho, chain, and ring phosphoric acids and their esters dissolved in the corresponding alcohol. Typical kinetic curves and the distribution of products obtained upon the cessation of condensation are also presented.