Condensation Reagent Research Articles

Preparation and properties of polyesteramide-graft-poly(2,6-dimethyl-1,4-phenylene oxide) copolymers

New tailor-made polyesteramide-graft-poly(2,6-dimethyl-1,4-phenylene oxide)(PPO) copolymers were prepared by direct polycondensation from a dicarboxy-terminated PPO macromonomer, aromatic dicarboxylic acids, diphenols, eicosanedioic acid and tolylene-2,4-diamine at definite mole ratios in pyridine including lithium chloride in the presence of diphenyl chlorophosphate as a condensation reagent and characterized by FTIR spectra, 1H and 13C NMR spectra and elemental analyses. Most of them were soluble in chloroform at room temperature in spite of the presence of amide linkage in the backbones. Differential scanning calorimetry measurements and optical texture observations by polarizing microscope described that only the graft copolymers containing a biphenyl unit show thermotropic nematic phases. Thermogravimetry-differential thermal analysis measurements showed that the copolymers are thermostable up to 290–300°C.

Chemical Synthesis of Oligodeoxyribonucleotides Using N-Unprotected H-Phosphonate Monomers and Carbonium and Phosphonium Condensing Reagents: O-Selective Phosphonylation and Condensation

Oligodeoxyribonucleotides were synthesized using H-phosphonate monomers without amino protection. The H-phosphonate monomers of deoxyadenosine, deoxycytidine, and deoxyguanosine bearing the free amino groups were synthesized in good yields by O-selective phosphonylation of the parent 5‘-O-(dimethoxytrityl)deoxyribonucleosides. It was found that the amino groups of the nucleosides were not modified during internucleotidic bond formation where (benzotriazol-1-yloxy)carbonium and -phosphonium compounds were employed as condensing reagents. The most effective condensing reagent for rapid internucleotidic bond formation was found to be 2-(benzotriazol-1-yloxy)-1,1-dimethyl-2-pyrrolidin-1-yl-1,3,2-diazaphospholidinium hexafluorophosphate (BOMP). In the present H-phosphonate method, 2-(phenylsulfonyl)-3-(3-nitrophenyl)oxaziridine (PNO) was employed as a new oxidizing reagent for the oxidation of internucleotidic H-phosphonate linkages under anhydrous conditions in the presence of N,O-bis(trimethylsilyl)acetamide. The reaction mechanism for the O-selective condensation was investigated in detail by means of 31P NMR spectroscopy. Unprecedented oxidation of the H-phosphonate monomers was observed during activation of the monomers with (benzotriazol-1-yloxy)phosphonium and -carbonium condensing reagents in the absence of the 5‘-hydroxyl components. A mechanism for the O-selective condensation was proposed on the basis of ab initio molecular orbital calculations for the model compounds at the HF/6-31G* level.

Synthesis and characterization of fluorinated poly(aryl ether ketone)s containing 1,4-naphthalene moieties

The new monomer 2,2-bis[4-(4-(4-fluorobenzoyl}-1-naphthoxy)phenyl]hexafluoropropane (2) was synthesized in a two-step reaction sequence. 2,2-bis[4-(1-naphthoxy)phenyl]-hexafluoropropane (1) was prepared using the Ullmann ether synthesis reaction of 4,4-(hexafluoroisopropylidiene)diphenol with 1-bromonaphthalene. Friedel-Crafts acylation of 1 with 4-fluorobenzoyl chloride in methylene chloride containing dimethylsulfone selectively afforded 2 in 82% yield. The polycondensation of 2 with various bisphenols in DMAc in the presence of an excess of potassium carbonate as a condensation reagent was carried out at 165°C to quantitatively afford the corresponding fluorinated poly(aryl ether ketone)s containing 1,4-naphthalene moieties. Thermal analysis of the polymers showed them to have T g s ranging from 194 to 230°C and to be thermally stable in air up with initial weight losses at about 500°C. In addition, these novel polymers exhibited excellent solubility in organic solvents including NMP, DMAc, and chloroform.

ChemInform Abstract: Phosphorodimorpholidic Halides as a New Condensing Reagent for the Formation of β‐Lactams from β‐Amino Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: A Facile Synthesis of a Sterically Congested Amide: A Convenient Method of Steroidal 17β‐Amide Synthesis from 17β‐Carboxylic Acid and a Hindered Amine with 2,4,6‐Triisopropylbenzenesulfonyl Chloride as a Condensing Reagent.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A Facile Synthesis of a Sterically Congested Amide: A Convenient Method of Steroidal 17β-Amide Synthesis from 17β-Carboxylic Acid and a Hindered Amine with 2,4,6-Triisopropylbenzenesulfonyl Chloride as a Condensing Reagent

Steroidal 17β-amides 2, 4, 6 were synthesized from the 17β-carboxylic acids 1, 3, 5 and sterically hindered amine in 88-100% yields using 2,4,6-triisopropylbenzenesulfonyl chloride as a condensing reagent. This method was successfully applied to the synthesis of sterically congested simple amide 8.

Synthesis and properties of poly(arylene-ether-ketone)s containing a dimethylnaphthalene skeleton in the main chain

The synthesis of novel dihaloarenes (1,5-bis(4-halophenyl)-2,6-dimethylnaphthalenes, 1), polycondensation of 1 with biphenols, and properties of the obtained polymers were described. Selectively Friedel-Crafts acylation of 2,6-dimethylnaphthalene with 4-halobenzoyl chlorides in nitrobenzene afforded 1 in high yields. X-Ray single-crystal structural analysis of 1 supported that the dibenzoylation proceeded regioselectively at the 1- and 5-positions and the two methyl groups sterically inhibited the coplanarity of the aromatic planes. The polycondensation of 1a with Bisphenol A in toluene/ N-methyl-2-pyrrolidone (NMP) mixed solvent in the presence of excess potassium carbonate as a condensation reagent was carried out at 180°C for several hours to quantitatively afford the corresponding poly(arylene-ether-ketone) (PEK) 3 with a high molecular weight ( M n −30,000) as a slightly yellow powder. To evaluate the effect of the methyl groups of 3, polycondensation of 2,6-bis(4-fluorobenzoyl)naphthalene 2 with Bisphenol A was carried out for comparison and the corresponding PEK 4 was obtained quantitatively. Whereas 3 was soluble in ordinary organic solvents such as tetrahydrofuran (THF) and chloroform at room temperature, 4 was insoluble in common solvents except for strong acids such as conc. sulfonic acid. 3 showed a high glass-transition temperature (238°C) and a 5% weight loss temperature of 457°C. The polycondensations of 1a with various biphenols such as dihydroxybenzophenone were carried out to examine the properties of the obtained polymers. The obtained PEKs showed high glass transition temperatures and 5% weight loss temperatures as well as good solubilities in ordinary organic solvents at room temperature. Casting of the polymers from THF solution gave transparent, tough, flexible, and amorphous films. 1,5-Bis(4-chlorobenzoyl)-2,6-dimethylnaphthalene 1b similarly underwent a polycondensation reaction with Bisphenol A to give the corresponding polymer quantitatively.

Sulfation of Polysaccharides with Sulfuric Acid Mediated by Dicyclohexylcarbodiimide

Abstract Starch, agarose, κ-carrageenan and porphyran were sulfated by sulfuric acid with dicyclohexylcarbodiimide as a condensation reagent. In all the cases, the sulfation at O-6 appeared to be predominant on the basis of results from methylation analyses. Although the reactivities of the other hydroxyl groups towards the present sulfation reaction were less than that at C-6, they varied depending on the position in the sugar residue of the polysaccharides. The sulfated agarose was further fractionated in terms of the difference in the solubility of its cetylpyridinium salt to KCl solution. The major fraction resembled the main polysaccharide of funoran (agarose 6-sulfate) on the basis of the behavior of its cetylpyridinium salt, 13C NMR measurements and methylation analyses.

New Synthetic Route to Phosphonic Acid Anhydrides

Abstract Phosphonic acid anhydrides are useful condensation reagents in the peptide and polyamide synthesis [1,2]. A new method for the preparation of well defined anhydrides is now described and intermediates of the peptide synthesis are elucidated. Cryoscopic and mass spectrometric data confirm the suggested cyclic trimeric molecular structure and the 31P{1H}- as well as 1H-NMR spectra can be explained with the structures: Reaction of t-BuP(O)(SiMe3)2 and PhBCl2 yields the mixed anhydride of t-butylphos-phonic and phenylboronic acid C40H57B4O12P4. The compound forms colourless crystals and the obtained data are in agreement with a 16 membered P-0-B- ring.

Novel optically transparent polyesters containing a high density of second-order non-linear optically active chromophores

The syntheses and second-order non-linear optical (NLO) properties of novel types of optically transparent polyesters containing a high density of second-order NLO-active chromophores are described. The chromophores used in this study contained either a perfluorooctyl- or an octyl-sulfonyl moiety as the electron-withdrawing group at the π-conjugating sites. The polyesters are prepared by condensation polymerization between isophthalic acid derivatives and 2-[N-(2-hydroxyethyl)-4-(perfluorooctylsulfonyl)anilino]ethanol by the use of triphenylphosphine and diethyl azodicarboxylate as the condensation reagents. The amorphous polyesters obtained, the optical transparency of which was down to 390 nm, exhibited good solubility in common organic solvents and provided optical-quality films by spin-coating. In addition, second-harmonic generation (SHG) measurements of spin-coated films of the polyesters were carried out by the Maker fringe method using a Q-switched Nd : YAG laser as the exciting beam after poling treatment. One of the polyesters, which was prepared from 5-{2-[N-methyl-4-(perfluorooctylsulfonyl)anilino]ethoxy}isophthalic acid and 2-[N-(2-hydroxyethyl)-4-(perfluorooctylsulfonyl)anilino]ethanol, exhibited the desired optical-transparency and a second-order NLO coefficient, d33, of 3.0 pm V–1.

Novel Types of Polyesters Containing Second-Order Nonlinear Optically Active Chromophores with High Density

This article describes the syntheses and second-order nonlinear optical (NLO) properties of novel types of polyesters containing second-order NLO active chromophores with high density, which were obtained by condensation polymerization using two comonomers with the N,N-dialkyl-4-nitroaniline or N,N-dialkyl-4-((4-cyanophenyl)azo)aniline moiety. The polyesters were synthesized by condensation polymerization between isophthalic acid derivatives and N-substituted diethanolamines using tri- phenylphosphine and diethyl azodicarboxylate as the condensation reagents in dimethyl sulfoxide (DMSO) or 1-methyl-2-pyrrolidinone (NMP). The obtained amorphous polyesters exhibited good solubility in common organic solvents and provided optical-quality films by spin-coating. The SHG measurements of the spin-coated films of the resulting polyesters were carried out by the Maker fringe method using a Q-switched Nd:YAG laser (1064 nm) as an exciting beam after corona-poling. One of the polyesters, which was prepared from 5-(2-(N-methyl-4-nitroanilino)ethoxy)isophthalic acid and N-(4-((4-cyanophenyl)- azo)phenyl)diethanolamine, exhibited the large second-order NLO coefficient, d33, of 202 pm/V. On the other hand, a polyester containing chromophore moieties with the highest density, which was prepared from 5-{(1,3-bis(4-((4-cyanophenyl)azo)-N-methylanilino)-2-propyl)oxy}isophthalic acid and N-(4-((4- cyanophenyl)azo)phenyl)diethanolamine, exhibited good temporal stability of the second-order nonlinearity at ambient temperature.

Cyclo(-arginyl-sarcosyl-aspartyl-phenylglycyl-)2. Simple synthesis of an RGD-related peptide with inhibitory activity for platelet aggregation

The dimerization–cleavage of the tetrapeptide precursor bound to the benzophenone oxime resin afforded cyclo[-Arg(Tos)-Sar-Asp(OcHex)-Phg-]2, a cyclic analogue of the RGD peptide. The yield and the selectivity between the tetra-/octa-peptide formed through the cyclization–cleavage depended on the sequence of the tetrapeptide. The ratio of tetra-/octa-peptide also depended on the substitution level of the oxime resin with the peptide segment. The cyclic octapeptide was also synthesized through the solution-phase dimerization–cyclization from the linear tetrapeptide precursor. The solution-phase dimerization–cyclization was very efficiently mediated with BOP/HOBt as the condensation reagent. 1H NMR and CD spectra suggested that the cyclic octapeptide was of some restricted conformation, which might be involved in the preferred formation of the octapeptide in both solid- and solution-phase syntheses. The octapeptide showed potent inhibitory activity toward platelet aggregation; however, it showed no activity toward cell adhesion.

Synthesis of a novel naphthalene‐based poly(arylene ether‐ketone) by polycondensation of 1,5‐bis(4‐fluorobenzoyl)‐2,6‐dimethylnaphthalene with bisphenol a

AbstractSynthesis of 1,5‐bis(4‐fluorobenzoyl)‐2,6‐dimethylnaphthalene (1), polycondensation of 1 with Bisphenol A, and properties of the obtained polymer were studied. Friedel–Crafts acylation of 2,6‐dimethylnaphthalene with 4‐fluorobenzoyl chloride in nitrobenzene selectivity afforded 1 in 82% yield. X‐ray single crystal structural analysis of 1 confirmed that the dibenzoylation proceeded regioselectively and two methyl groups sterically inhibited the coplanarity of the two aromatic planes. The polycondensation of 1 with Bisphenol A in toluene/N‐methyl‐2‐pyrrolidone (NMP) mixed solvent in the presence of excess potassium carbonate as a condensation reagent was carried out at 180°C for 4 h to quantitatively afford the corresponding poly(arylene ether‐ketone) (PEK) 3 with high molecular weight (M̄n∼30,000) as a slightly yellow powder. As the reaction time was prolonged, both M̄n and MWD of 3 increased and the solubility of 3 in chloroform clearly decreased. By GPC‐LALLS, M̄n of 3 obtained by the polycondensation for 16 h, was 85,000. The PEK 3 with high molecular weight was produced in a quantitative yield in a variety of solvents such as sulfolane. Water formed during the polycondensation hardly affected the yield and molecular weight of 3, although a small molecular weight decrease took place. To evaluate the special effect of the methyl groups of 3, polycondensation of 2,6‐bis(4‐fluorobenzoyl)naphthalene 2 with bisphenol A was carried out for comparison and the corresponding PEK 4 was quantitatively obtained. Whereas 3 was soluble in ordinary organic solvents such as tet‐rahydrofuran (THF), chloroform, and NMP at room temperature, 4 was insoluble in most solvents except for strong acids such as conc. sulfonic acid. The polymer 3 showed high glass transition temperature (238°C) and 5% weight loss temperature (457°C). Casting of the polymer from THF solution gave a transparent, tough, flexible, and amorphous film. © 1995 John Wiley & Sons, Inc.

Thermotropic liquid‐crystalline aromatic polyester‐graft‐poly(2,6‐dimethyl‐1,4‐phenylene oxide) copolymers

AbstractDicarboxy‐terminated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) macromonomers were prepared and subjected to the preparation of tailor‐made aromatic thermotropic liquid‐crystalline (LC) polyester‐graft‐PPO copolymers. The macromonomers were obtained by hydrolysis of dimethyl carboxylate‐terminated PPO macromonomers without cleavage of the PPO chains, which were derived from PPO oligomers with a terminal phenolic OH‐group and a bromo derivative of isophthalate. The tailor‐made aromatic thermotropic LC graft copolymers were prepared by direct polycondensation from the dicarboxy‐terminated macromonomers, p‐hydroxybenzoic acid, aromatic dicarboxylic acids and diphenols at definite mole ratios in pyridine in the presence of diphenyl chlorophosphate as a condensation reagent. The polyester‐graft‐PPO copolymers are thermally stable up to 280–300°C and show a thermotropic LC nematic phase in spite of introduction of PPO grafts on the polyester backbones.

A low-epimerizing peptide coupling reagent based on the rearrangement of a carboxylic-sulfonic mixed anhydride

A series of peptides has been prepared using an o-hydroxybenzenesulfonyl chloride as the condensation reagent. Experimentally, the coupling is a one pot two-steps reaction: formation and aminolysis of a substituted aryl ester. The first step occurs by an elimination-addition reaction involving a sulfoquinone intermediate, followed by an efficient six-membered acyl transfer reaction in the phenolic carboxylic-sulfonic mixed anhydride intermediate. The Young and Anteunis tests show that the degree of epimerization is very low in methylene chloride and acetonitrile.

ChemInform Abstract: Electron‐Rich Triarylbismuthines as Selective Condensation Reagent Under Neutral Conditions. Condensation of Aliphatic Carboxylic Acids with Amines and Alcohols.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Synthesis of a New Saccharin Derivative (BID‐SPy) and Its Utilization as a Condensing Reagent in the Preparation of Dipeptides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Electron-rich Triarylbismuthines as Selective Condensation Reagent under Neutral Conditions. Condensation of Aliphatic Carboxylic Acids with Amines and Alcohols

Abstract On heating with amines or alcohols in the presence of tris(2-methoxy phenyl)- or tris(2,6-dimethoxyphenyl)bismuthine, carboxylic acids bearing α-hydrogen are readily converted into the corresponding amides or esters in good yields while those without α-hydrogen remain intact.

Dipeptide-derived lariat ethers as enantioselective carriers of Z-amino acid and dipeptide carboxylates

Abstract Lariat ethers bearing N-pivot dipeptide arms have been designed and synthesized as models of natural amino acid and Na+ cation carriers, the “symporters”. Two types of dipeptide derived lariats have been prepared: those having amino terminal dipeptide arms (ATD-lariats, 6, 7, 10, 11, 16–18) and those having carboxylic group terminal dipeptide arms (CTD-lariats, 12, 19). ATD-lariats were synthesized by N-acylation of aza-15-crown-5, aza-18-crown-6, and 4,13-diaza-18-crown-6 with Z-GlyOH or Z-PhgOH (Phg = d-α-phenylglycine) in the presence of DCC or Ph3P/CCl4/Et3N condensation agents, subsequent hydrogenolytic removal of Z-protecting groups, and the introduction of a second Z-amino acid unit using the same condensation reagents. CTD-lariats 12 and 19 were obtained by N-alkylations of aza-18-crown-6 and 4,13-diaza-18-crown-6 with methyl N-(chloro-acetyl)-d-α-phenylglycinate (acetonitrile, Na2CO3, NaI). The binding affinities of ATD-lariats toward Na+ and K+ assessed in anh. MeOH and compared with th...

ChemInform Abstract: Diethyl Bromophosphate as a New Condensing Reagent for the Formation of β‐Lactams from β‐Amino Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.