Chemical modification of polynorbornene. II. Extended sulfonation processes

In the sulfonation of polynorbornene in dilute solution, the nature of the sulfonation agent mainly influences the reaction rate, according to its strength and also affects some side reactions (chain scission and crosslinking). The sulfonation can be carried out in suspension after swelling the highly porous powder in dichloroethane up to a 55% sulfonation ratio with preservation of the initial particular nature of the polymer; the latter may be then either partly or totally water soluble, depending on the initial size of the particles. Partial sulfonation, leading to ionomers, may be carried out in bulk at moderate temperature, in a mixing chamber, after gelification of the polymers, plasticized with CCl₄.     

Chemical modification of fumagillin. II. 6-Amino-6-deoxyfumagillol and its derivatives.

6-Amino-6-deoxyfumagillol (5) was synthesized by reductive amination of 6-oxo-6-deoxyfumagillol (4), which was obtained by oxidation of fumagillol (2). The reduction proceeded stereoselectively by the equatorial attack of hydride and 5 was found to have the same stereochemistry as that of 2. Several derivatives of 5 were prepared and most of them showed anti-angiogenic activity comparable to that of fumagillol derivatives.     

Synthesis of monodisperse hydroxyl-containing polystyrene via chemical modification

A facile synthesis of linear monodisperse hydroxyl-containing polystyrene, poly{styrene-co-[p-(1-hydroxyethyl)styrene]} and poly{styrene-co-[p-(2-hydroxypropan-2-yl)styrene]}, was carried out via chemical modification of polystyrene by a two-step procedure, i. e. monodisperse polystyrene was acetylated under mild conditions, followed by processes of reduction with LiAlH₄ and addition with CH₃MgBr, respectively. ¹H NMR and FTIR spectra showed that in both cases, the reaction of acetyl to hydroxyl is complete. Sizeexclusion chromatography demonstrated that both molecular weight and monodispersity of the final products were basically unchanged.     

Functional group modification via organotellurium chemistry. Synthesis of allyl alcohols from chloromethyloxiranes.

Treatment of 2-substituted-2-chloromethyloxiranes with telluride ion gives 2-substituted allyl alcohols, presumably through an epitellurlde intermediate.     

Benzoxazolinones. II. Synthesis of 3-vinylbenzoxazolinones and 3-vinylbenzoxazolinethione

A method has been developed for obtaining 3-vinylbenzoxazolinones and 3-vinylbenzoxazolinethione. It has been shown that it is also possible to obtain 3-methylbenzoxazolinethione by this method in good yield (76%).     

Benzoxazolinones. II. Synthesis of 3-vinylbenzoxazolinones and 3-vinylbenzoxazolinethione

A method has been developed for obtaining 3-vinylbenzoxazolinones and 3-vinylbenzoxazolinethione. It has been shown that it is also possible to obtain 3-methylbenzoxazolinethione by this method in good yield (76%).Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 553–556, July–August, 1980.     

Synthesis of Polyfunctionalized Pyrroles via Green Chemical Methods

Water was found to be an excellent solvent for the one‐pot synthesis of tetrasubstituted pyrrole derivatives under ultrasound involving the standard Knoevenagel condensation followed by the Michael type reaction. A new catalyst free system, excellent atom economy, ultrasound in water medium, short reaction times, good yields (88–93%), and ease of workup make this protocol more attractive and economically viable. The resulting substituted pyrroles are characterized by ¹H and ¹³C NMR, elemental analysis, and mass spectral data.     

Oligonucleotides containing arylacetylene residues: Synthesis and post-synthetic modification via [3+2] cycloaddition

The synthesis of a phosphoramidite reagent for 5′-modification of oligonucleotides by introducing an arylacetylene residue has been described. Using the reaction with 3-(perylen-3-yl)propyl azide as an example, it was shown that the acetylene derivatives of oligonucleotides synthesized using this reagent undergo Cu^I-catalyzed [3+2] dipolar cycloaddition. Fluorescent conjugates were obtained in high yields and characterized by mass spectra. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1220–1226, July, 2006.     

Crystallization of bisphenol-A polycarbonate induced by organic salts: Chemical modification of the polymer. II. Model reactions

In the presence of sodium o-chlorobenzoate, bisphenol-A diphenylcarbonate (BADPC) undergoes complex chemical modifications from 170°C. Reaction between BADPC and minute amounts of salt produces sodium phenoxide end groups which undergo a fast exchange reaction with the carbonate groups of BADPC. In a closed system, an equilibrium molecular weight distribution is progressively attained which agrees fairly well with the one predicted from a simple model based on Bernoulli statistics. In an open system, the equilibrium is continuously displaced by the evaporation of volatile diphenyl carbonate. This leads to a steady increase of the molecular weight.     

Chemical modification of estafiatin

The halogenation, epoxidation, acetylation, and oxidation of the sesquiterpene--lactone estafiatin (I) has given eight derivatives. It has been shown that during the epoxidation of estafiatone (IV) the formation of a -lactone takes place as the result of the Bayer-Villiger oxidation of the cyclopentanone fragment. A stereoselective conversion of estafiatin into the known natural guaianolide isozaluzanin C is described. The structures of the derivatives synthesized were established on the basis of their IR, UV, PMR, and mass spectra.Institute of Organic Synthesis and Coal Chemistry, Kazakh Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 648–653, September–October, 1991.     

Chemical modification of estafiatin

A high reactivity of the olefinic double bonds of the lignin (Lg) macromolecule in the reaction with molecular chlorine has been found which has permitted the chlorination of Lg to be carried out under cryogenic conditions at 150–250 K. The process takes place by a radical-chain mechanism with a length of the kinetic chain of approximately 1000 units. The bulk of the chlorine is consumed in the olefinic chains of the Lg. Other reaction products besides chlorolignin are hydrogen chloride and phenoxyl radicals, which have singlet ESR spectrum (H=1.0–1.2 mT) and are retained in the chlorinated samples of Lg to 250 K.Institute of Chemical Physics, Academy of Sciences of the USSR, Chernogolovka, Moscow Province. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 671–676, September–October, 1990.     

Chemical modification of argolide

Chemical transformations have been made of argolide, a sesquiterpene lactone of the germacrane type, as a result of which new epoxy, amino, and hydroxy derivatives of it have been obtained.Institute of Phytochemistry, Academy of Sciences of the Republic of Kazakhstan, Karaganda, fax (3212) 433144, e-mail: arglabin@phyto, karaganda, su. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 188–192, March–April, 1999.     

Chemical Reactions on Polymers. II. Modification of Diene Polymers with Triazolinediones via the Ene Reaction

A wide variety of polymers and copolymers of 1,3-dienes have been modified at low temperatures via the ene reaction with 4-substituted l,2,4-triazoline-3,5-diones. The resulting modified polymers were characterized via infrared spectroscopy, nuclear magnetic resonance, intrinsic viscosity, gel-permeation chromatography, differential scanning calorimetry, solubility tests, and tensile measurements. Physical properties measurements support the postulate that the highly polar pendant urazole groups contribute inter molecular and intramolecular hydrogen-bonding interactions and thus impart to the modified polymers thermoplastic elastomer properties. Changes in the solubility character, thermal behavior, and tensile properties of the modified polymers are in accord with this postulate. Since the association between molecules is physical in nature, the modified polymers remain soluble in appropriate solvents. They also show dramatic decreases in molecular size; for example, the average molecular size of polymers at 1% modification is about one tenth that of the unmodified polymer due to intramolecular interactions, a size reduction of the same order of magnitude as that of chemically crosslinked polymers. Poly-1,2-butadiene, when modified to the extent of 5%, gave values for elongation to break, Young's modulus, and tensile strength twice those for the parent polymer, while tensile recoveries were > 90%.     

Polymeric mesoions, 3. Synthesis of polymeric mesoionic 1,3-diazinium-olates via polymer analogous modification of a polythiourea from m-phenylenediamine and p-phenylene diisothiocyanate

Mesoionic poly(1,1′-(1,3-phenylene)-3,3′-(1,4-phenylene)-bis(5-decyl-2-decylthio-4,6-dioxo-1,3-diazine)) ( 6 ) was prepared by cyclisation of the isothiourea component of poly(1,1′-(1,3-phenylene)-3,3′-(1,4-phenylene)-bis(2-decylisothiourea)) ( 4 ) with decylmalonic acid (5) by use of dicyclohexylcarbodiimide (DCC). Polymer 4 was obtained by polymer analogous alkylation of poly(1,1′-(1,3-phenylene)-3,3′-(1,4-phenylene)-bisthiourea) ( 3 ). For comparison of spectroscopic data, 5-butyl-2-propylthio-4,6-dioxo-1,3-diphenyl-1,3-diazine ( 9 ) was synthesized as low molecular weight model compound.     

Chemical modification of the surface of cellulosic fibres. 2. Introduction of alkenyl moieties via condensation reactions involving isocyanate functions

Various cellulosic substrates including powders, long fibres and sheets were treated with isocyanates bearing an alkenyl function in a non-swelling medium. These heterogeneous reactions introduced a small but significant number of polymerizable moieties at the surface of the cellulose. In a second step, the free radical polymerization of styrene or methyl methacrylate was carried out in the presence of these modified cellulosics. It was shown that the alkenyl functions appended onto their surface took part in the chain growth thus giving a continuous path of covalent bonds between the solid substrate and the polymer matrix. 0969--0239 © 1998 Blackie Academic & Professional