Development of chlorotriazine polymer dehydrocondensing reagents (Poly-Trzs)

Polymer-type dehydrocondensing reagents comprising of a triazine dehydrocondensing reagent, itself in a polymerized form (Poly-Trz—MMs'), have been developed by exploiting the chemical properties of cyanuric chloride that readily binds to alcohol or amines. A chlorotriazine polymer bearing two alkoxy substituents at the 4- and 6- positions (Poly-O-Trz-Cl) was prepared by alternating copolymerization between cyanuric chloride and tetra(ethylene glycol). Similarly, polymers bearing both alkoxy and amino substituents (Poly-N-Trz-Cl) were synthesized from tetra(ethylene glycol) bis(4,6-dichlorotriazin-2-yl) ether 6 and tris(2-aminoethyl)amine 7 and/or ethylenediamine 8. All the polymers were shown to be good reagents for dehydrocondensation of carboxylic acids and amines in the presence of NMM, compared to the corresponding monomeric dehydrocondensing reagent (DMT-MM). The advantages of the polymeric reagents are as follows: (1) both the reaction and isolation procedure of dehydrocondensation can be greatly simplified, (2) the dehydrocondensation can be conducted in protic solvents as well as in common organic solvents, (3) the reagents can be efficiently prepared at a low cost, and (4) these reagents are considered eco-friendly, generating a lower amount of waste compared to conventionally related reagents because of high loading of the dehydrocondensing activity (ca. 3 mequiv/g).     

Immobilized triazine-type dehydrocondensing reagents for carboxamide formation: ROMP-Trz-Cl and ROMP(OH)-Trz-Cl

New triazine-type dehydrocondensing reagents, such as ROMP-Trz-Cl and ROMP(OH)-Trz-Cl, were synthesized by a ring opening metathesis polymerization (ROMP) method, and these showed higher loading than conventional polymer-supported condensing reagents. These polymers effect the formation of amides in good yields by addition of a mixture of carboxylic acid, amine and NMM. ROMP(OH)-Trz-Cl, which contains hydroxyl groups in the polymer chain, gave amides in good yields even in MeOH.     

Immuno-arrays for multianalyte analysis of chlorotriazines

In this paper, a novel strategy for multicomponent analysis of two classes of pesticides such as triazines (atrazine and simazine) and phenoxyalkanoic acids (2,4-dichlorophenoxy acetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 4-chlorophenoxyacetic acid (CPOAc), phenoxyacetic acid (POAc)) employing immuno-arrays is demonstrated. The approach is based on cross-reactive arrays of specific antibody pairs coupled to chemometric pattern recognition. The monoclonal antibody pairs employed in this work (atrazine-simazine and 2,4-D) are specific towards a set of analytes and preclude a particular set of others present in the sample matrix. Antibody pairs of atrazine, simazine, and 2,4-D are used to discriminate and quantify analyte of interest. Atrazine was quantified in presence of trace concentration of simazine and that of 2,4-D. The combinatorial cross-reactivity of antibody pairs towards simazine, atrazine and 2,4-D is used to distinguish among different classes of analytes and their influence on the signal suppression in immuno-techniques. These sensors exclude recognition by carbamates such as carbaryl and carbofuran.     

Palladium-catalyzed cross-coupling reaction of resin-bound chlorotriazines

To introduce the biaryl structure as a triazine functionality, we have developed a new synthetic route via the Suzuki cross-coupling reaction of resin-bound chlorotriazines. The Suzuki cross-coupling reaction was achieved using various arylboronic acids, Pd(PPh₃)₄, Cs₂CO₃, and dioxane. With the integration of this chemistry and our previous orthogonal methodology, the triazine library is greatly expanded to a biaryl scaffold.     

Catalytic reactions of oxetanes with protonic reagents and aprotic reagents leading to novel polymers

This paper reports new addition reactions of oxetanes with certain protonic reagents such as carboxylic acid, phenol, and thiol, and with certain aprotic reagents such as acyl chloride, thioester, phosphonyl dichloride, silyl chloride, and chloroformate using quaternary onium salts as catalysts. The kinetic study of the addition reactions of oxetanes was also investigated. These new addition reactions were applicable to the synthesis of new polymers. These polyaddition systems could also construct both polymer main chains and reactive side chains. The alternating copolymerization of oxetanes with carboxylic anhydride was performed. Furthermore, it was found that anionic ring‐opening polymerization of oxetanes containing hydroxy groups proceeded to afford the hyperbranched polymer (HBP) with an oxetanyl group and many hydroxy groups at the ends of the polymer chains. Alkali developable photofunctional HBPs were synthesized by the polyaddition of bis(oxetane)s or tris(oxetane)s, and their patterning properties were examined, too. The photo‐induced cationic polymerization of the polymers with pendant oxetanyl groups and the thermal curing reactions of polyfunctional oxetanes (oxetane resins) were also examined to give the crosslinking materials quantitatively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 709–726, 2007     

Development of a simple system for dehydrocondensation using solid-phase adsorption of a water-soluble dehydrocondensing reagent (DMT-MM)

It has been indicated that hydrophilic solid powder to which aqueous solution of a novel dehydrocondensing reagent DMT-MM is adsorbed becomes a simple solid-phase dehydrocondensing reagent of low cost. Reaction in a liquid--liquid biphasic system on the surface of a solid phase with a large area was accelerated by suspending this powder in a dichloromethane solution of a carboxylic acid and an amine to be condensed. The reaction was rapid with a high yield despite the heterogeneity of the system. Like general solid-phase reagents, a hydrophobic carboxamide alone could be isolated at a relatively high purity only by filtration of the resulting suspension of reaction mixture.     

Transmetalation as a route to novel styryllithium reagents

[structure: see text] Transmetalation of beta-tributyl(styryl)stannanes with n-BuLi gives the functional equivalents of the corresponding styryllithium intermediates. Reaction of the intermediates with chlorotrimethylsilane, iodomethane, or dimethyl sulfate gives the substituted styryl products in moderate to good yields. In all cases, the configuration about the double bond was retained in the products.     

Palladium-catalyzed novel addition-elimination reaction of alkenyltin reagents to norbornene

Palladium-catalyzed reaction between 1-alkenyltin trichlorides and norbornene resulted in stereoselective formation of 3-alkylidenepentacyclo[9.2.1.^5,81.^1,110.^2,100^4,9]pentadecane instead of an expected simple alkenylstannylation product. Generation of trichlorostannane and its decomposition product, tin(II) chloride, was confirmed by trapping it with methyl propiolate and norbornene and analysis of the reaction by ¹¹⁹Sn NMR, respectively.     

Synthesis of novel DOXYL labelling reagents with electrophilic groups

The oxalic acid salt of 2-aminomethyl-3-oxyl-2,4,4-trimethyl-1,3-oxazolidine has been synthesised from 1-chloroacetone. Being water soluble, the salt is a promising candidate for varied applications. It has been functionalised with electrophilic groups generating novel spin labelling reagents.     

Diversity-oriented synthesis of novel polycyclic scaffolds using polymer-bound reagents

A concise sequence utilizing a Petasis three component reaction followed by a tandem aza-Cope-Mannich cyclization afforded novel polycyclic heterocycles in good yield; alternative iminium cyclization based on a Pictet-Spengler reaction or aminal formation led to divergent pathways affording skeletal diversity.     

Triphenylbismuth diacylates as novel reagents for fine organic synthesis

Triphenylbismuth diacylates, Ph₃Bi(O₂CR)₂ (R = Me, Et, Ph, CF₃, CH=CH₂), are novel effective reagents for fine organic synthesis. They oxidize primary and secondary alcohols and di-tert-glycols under mild conditions to form the corresponding carbonyl compounds in high yields;O- andN-phenylate alcohols, enols, and amines; andO- ando-C-phenylate phenols.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2043–2047, December, 1993.     

Synthesis and conformational analysis of novel trimeric maleimide cross-linking reagents

Nine homotrifunctional cross-linking reagents are presented. Their synthesis and chemical properties as well as their characterization by classical mechanical conformational searching techniques is reported. Mixed Low Mode and Monte Carlo searching techniques were used to exhaustively sample the OPLS2005/GBSA(water) potential energy surface of trisubstituted cyclohexane and benzene derivatives of C3 symmetry. Geometric structure, molecular length, and hydrogen-bonding patterns were analyzed. Nonaromatic compounds exhibited exclusively chair conformations at low energies, with a preference for axial or equatorial arms depending upon the presence of additional ring substituent Me groups. Increasing chain length often resulted in overall shorter molecular length due to additional chain flexibility. These results were consistent with one- and two-dimensional temperature-dependent NMR studies.     

Determination of chlorotriazines, methylthiotriazines and one methoxytriazine by SPE-LC-UV in water samples

Triazine herbicides form a wide group of substances that belong among the most common agrochemicals applied for pre- and post-emergence weed control. So, they can be found in the environment at trace level. In order to determine their concentrations in water samples by the usual analytical techniques, a preconcentration step is commonly necessary. In this paper, a simple analytical method for the quantification of eight triazines (three chlorotriazines, four methylthiotriazines and one methoxytriazine) in water samples by solid phase extraction-reversed phase liquid chromatography (LC) has been developed. LC shows good analytical performance for simultaneous multiple triazine analysis (repeatability <2%, reproducibility <3%), except for prometon (repeatability 5.52%, reproducibility 16%). The results, obtained by using carbograph and polymeric sorbents for solid phase extraction (SPE), have been compared. The limits of quantification achieved permit the application of the proposed SPE-LC method for the determination of eight triazines in water samples (0.0065-0.028 μg l⁻¹).     

Particle-stabilized emulsions comprised of solid droplets

We kinetically stabilize oil-in-water emulsions comprising paraffin crystals by adsorbing solid particles (silica) of colloidal size at the oil/water interface. We obtain a set of emulsions that are quiescently stable for a long period of time (months), while the same emulsions are destabilized after only a few hours in the presence of surfactant molecules alone. The emulsions are submitted to a shear stress in order to probe their stability under flow conditions. Partial coalescence and gelation occur when the shear is applied for a sufficiently long period of time. The experiments reveal the existence of a critical droplet mass fraction, phi*, that defines a sharp transition between slow and fast gelation. The process of gelation is rather slow for phi < phi*, occurring at the scale of hours, and becomes almost instantaneous above phi*.     

Enzymatic synthesis and the structure elucidation of novel trisaccharides comprised of D-galactose,N-acetyl-D-glucosamine,and D-fructose

Enzymatic synthesis of trisaccharides from N-acetylsucrosamine and lactose utilizing the transgalactosylation activity of Aspergillus oryzae β-galactosidase provided two reaction products. Structure analyses by various 2D NMR spectroscopy and MS indicated that the products were β-D-fructofuranosyl β-D-galactopyranosyl-(1→6)-2-acetamido-2-deoxy-α-D-glucopyranoside and β-D-galactopyranosyl-(1→6)-β-D-fructofuranosyl-(2?1)-2-acetamido-2-deoxy-α-D-glucopyranoside. Moreover, J-resolved-HMBC experiments indicated that the conformations around the glycosidic bonds of these trisaccharides were very similar. Examination about the pH and thermal stabilities of the glycosidic bonds in the GlcNAc–Fru moiety of the two trisaccharides indicated apparent difference.     

Glycosyl disulfides: novel glycosylating reagents with flexible aglycon alteration

[reaction: see text] Glycosyl disulfides have been shown for the first time to be effective glycosyl donors. Glucosylation and galactosylation of a panel of representative alcohol acceptors allowed the formation of 28 simple glycosides, disaccharides, and glycoamino acids in yields of up to 90%. As well as providing a novel class of effective glycosyl donors, the ability to easily alter the nature of the aglycon and the ability to differently activate donors that differ only in their aglycon simply through altering conditions lends glycosyl disulfide donors to their use in latent-active reactivity tuning strategies.