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The stereospecificity of the cyclization reaction of (E)- and (Z)-2-alkenyl esters and amides of ethenetricarboxylate has been examined. The reaction of (E)/(Z)-2-butenyl esters with Al[Cl.sub.3] or Fe[Cl.sub.3] gave trans-substituted chlorinated [gamma]-lactone diastereomers stereospecifically. (E)/(Z)-2-butenyl and pentenyl amides undergo an intramolecular ene reaction at room temperature gradually. At 80[degrees]C, the (Z)-alkenyl amides were transformed to ris-substituted ene adducts and the (E)-amides were transformed to cis- and trans-substituted ene adduct mixtures. The reaction of (E)/(Z)-2-alkenyl amides with Zn[I.sub.2] gave trans-substituted [gamma]-lactam diastereomers stereospecifically along with the ene adducts. Key words: stereospecificity, ethenetricarboxylate, cyclization, halogenation, ene reaction. Nous avons etudie la stereospecificite de la reaction de cyclisation d'esters de (E)-2-alcenyle et de (Z)-2-alcenyle et d'amides d'ethenetricarboxylate. La reaction d'esters de (E)/(Z)-2-butenyle avec l'Al[Cl.sub.3] ou le Fe[Cl.sub.3] a produit de maniere stereospecifique des diastrereoisomeres trons-substitues chlores de [gamma]-lactone. A temperature ambiante, les amides de (E)/(Z)-2-butenyle et de (E)/(Z)-2-pentenyle ont graduellement subi une reaction ene intramoleculaire. A 80[degrees]C, les amides de (Z)-alcenyle se sont transformes en adduit ene cis-substitue, tandis que les amides de (E)-alcenyle ont forme en un melange d'adduits ene cissubstitues et trons-substitues. La reaction des amides de (E)/(Z)-2-alcenyle avec le ZnI2 a produit de maniere stereospecifique des diastereoisomeres trons-substitutees de [gamma]-lactame ainsi que les adduits ene. [Traduit par la Redaction] Mots-cles : stereospecificite, ethenetricarboxylate, cyclisation, halogenation, reaction ene., Introduction Substituted tetrahydrofurans and pyrrolidines are important heterocycles due to their frequent appearance in a broad range of bioactive natural products and pharmaceuticals. (1,2) Several synthetic strategies have been developed [...]

An ultra HPLC--diode array detector (UHPLC--DAD) method was developed and validated for rapid determination of cholesteryl-hexahydrophthaloyl-5-fluorouracil (CH5F) conjugate in standard drug, lipid nanoemulsion and dissolution samples. The chromatographic identification of this conjugate was achieved on Hypersil GOLD 50 x 2.1 mm reversed phase C18 column having a 1.9 pm packing as a stationary phase using methanol-water (80 : 20, v/v) as a mobile phase, at a flow rate of 0.4 mL/min with DAD detection at 276 nm. The proposed UHPLC--DAD method is linear in the concentration range of 1-50 µg/mL with correlation coefficient of 0.998. The proposed method is precise, accurate, robust, sensitive and specific for analysis of the conjugate. High assay value (98.7%) of CH5F conjugate in lipid nanoemulsion was obtained by the proposed method. Forced degradation studies indicated that conjugate was sufficiently stable under oxidative stress conditions degraded under acid, base and thermal stress conditions. The proposed UHPLC-DAD method successfully and resolved drug conjugate peak in the presence of its degradation products which established stability and indicating property of the method. Results of the present study indicated that the proposed UHPLC--DAD method can be successfully used for routine determination of CH5F conjugate in standard drug and pharmaceutical formulations. Keywords: UHPLC--DAD, cholesteryl-hexahydrophthaloyl-5-fluorouracil, lipid nanoemulsion, dissolution DOI: 10.1134/S1061934815050056, 5-Fluorouracil (5-FU) is a very common anticancer drug belonging to antimetabolite class that is recommended clinically for the management and treatment of various kinds of tumors like colorectal, breast and [...]

The hydrolytic reactivity of simple phosphate diesters with very good leaving groups is known to be practically independent of the nonleaving group at 100°C. Calculations on the (too slow to measure) hydrolysis at 25°C of a series of p-nitrophenyl diesters [ROPO.sup.-.sub.2]-OpNP with a wide range of nonleaving group OR indicate a small but significant effect at the lower temperature, making the R = methyl ester the most reactive. This is in the opposite sense to the much larger effect observed for the reactions of triesters and consistent with a reaction driven primarily by leaving group departure. The calculations use a continuum model with up to four discrete water molecules: two or three waters give the best results. Key words: phosphate diesters, hydrolysis, mechanism, bond length, calculation. On sait que la reactivite hydrolytique de diesters de phosphate simples comportant de tres bons groupes partants ne depend presque pas des groupes non partants a 100°C. Des calculs effectues sur l'hydrolyse (trop lente pour etre mesuree) a 25°C d'une serie de diesters de p-nitrophenyl (ROPO--OpNP) possedant une grande variete de groupes non partants (OR) mettent en evidence un effet faible mais significatif a basse temperature, qui fait du methylester le groupement (R) le plus reactif. Cela est en contradiction avec l'effet, beaucoup plus important, que l'on observe dans le cas des reactions des triesters et correspond davantage a une reaction essentiellement provoquee par le depart de groupes partants. Les calculs font appel a un modele continu comportant jusqu'il quatre molecules d'eau discretes. Les meilleurs resultats sont obtenus avec deux ou trois molecules d'eau. [Traduit par la Redaction] Mots-cles : diesters de phosphate, hydrolyse, mecanisme, longueur de liaison, calcul., Introduction Diester anions are well known to be among the least reactive phosphate esters. With [pK.sub.a]s typically between 1 and 2, the acid forms (RO)2P(O)OH exist in water as the [...]

Using trimethylsilyl (TMS) and tert-butyldimethylsilyl (TBDMS) derivatives of methylphosphonic acid and methylphosphonic acid esters, a comparative study of two ionization methods, namely, atmospheric pressure photoionization (APPhI) and photochemical ionization (APCPhI), in gas chromatography/mass spectrometry has been performed. It has been shown that, in the case of APPhI, the mass spectra of TMS and TBDMS derivatives contained only peaks corresponding to [[M + 73].sup.+] and [[M + 115].sup.+] (or [[M + Si[(Me).sub.3]].sup.+] and [[M + Si([sup.t]Bu)[(Me).sub.2]].sup.+] ions, respectively, where M is the molecular mass of a respective TMS or TBDMS derivative of methylphosphonic ester). APCPhI mass spectra recorded in the presence of acetone as a reagent substance consisted of only peaks of [[M + H].sup.+] and [[M + [M.sub.A] + H].sup.+] ions ([M.sub.A] is acetone molecule). The corresponding detection limits for silylated derivatives in APPhI and APCPhI were 30-125 pg and 1.1-23 pg, respectively (depending on the analyte). Keywords: atmospheric pressure photo- and photochemical ionization mass spectrometry, silyl derivatives of methylphosphonic acid DOI: 10.1134/S1061934814140135, INTRODUCTION Gas chromatography/mass spectrometry (GC-MS) with electron ionization is a standard method of analysis of products of transformations of organophosphorus chemical agents. Analyses by this method are performed after the [...]

Benzyl esters are cleaved upon reaction with Sn[Cl.sub.4], resulting in isolation of the corresponding carboxylic acid. Importantly, benzyl ethers, amines, and amides do not undergo debenzylation under these conditions, nor do a variety of other common protecting groups for alcohols, thereby rendering Sn[Cl.sub.4] selective amongst Lewis acids. The scope, tolerance, and limitations of the strategy are demonstrated through the analysis of several multifunctional substrates, including those bearing Cbz groups. Key words: benzyl ester, deprotection, protecting group, chemoselective debenzylation. Les esters de benzyle sont clives en reagissant avec le Sn[Cl.sub.4], ce qui a pour effet d'isoler l'acide carboxylique correspondant. Il est important de noter que les ethers, amines et amides benzyliques ne subissent pas de debenzylation dans ces conditions ni ne forment d'autres groupes communs protecteurs des alcools, ce qui a pour effet de rendre l'acide de Lewis Sn[Cl.sub.4] selectif. La portee, la tolerance et les limites d'une telle methode sont prouvees par l'analyse de plusieurs substrats multifonctionnels, dont ceux porteurs de groupes carboxybenzyles. [Traduit par la Redaction] Mots-cles: ester de benzyle, deprotection, groupe protecteur, debenzylation chimioselective., Introduction The use of protecting groups is essential to much of modern organic chemistry, despite admirable examples of natural product syntheses that lean to the contrary. (1) The benzyl protecting [...]

Studies toward the synthesis of trichoaurantianolide C (5) are described. Stille cross-coupling reactions of (E)- and (Z)-β-stannyl-α,β-unsaturated esters with allylic acetate 32 provide for the stereocontrolled formation of nonconjugated 2,5-diene-1-ols. Studies of the asymmetric Sharpless epoxidation are utilized to establish diastereofacial selectivity for the preparation of a crucial [C.sub.2] tertiary allylic alcohol for subsequent esterification and ring-closing metathesis. [SmI.sub.2] reductive cyclization of the key butenolide precursor 49 led to formation of the central seven-membered ring of the tricyclic core of the natural product. Key words: π-allyl Stille cross-coupling, reductive cyclization, stereoselective synthesis. On decrit une serie d'etudes realisees dans le but de faire la synthese du trichoaurantianolide C (5). Des reactions de couplages croises de Stille entre des esters (E)- et (Z)-β-stannyl-α,β-insatures et l'acetate allylique 32 conduisent a la formation stereocontrolee de 2,5-dien-1-ols non conjugues. On a utilise les methodes d'epoxydation asymetrique de Sharpless pour determiner la selectivite diastereofaciale pour la preparation d'un alcool allylique tertiaire en [C.sub.2] crucial pour l'esterification subsequente et la reaction de metathese qui permet d'effectuer la fermeture du cycle. La cyclisation reductrice a l'aide de [SmI.sub.2] du precurseur butenolide cle 49 conduit cycle central a sept chainons de la partie tricyclique fondamentale du produit naturel. Mots-cles: couplage croise π-allylique de Stille, cyclisation reductrice, synthese stereoselective. [Traduit par la Redaction], Introduction Natural products of the dolabellane and dolastane families have been studied as significant targets for synthesis because they present a number of interesting structural features as well as an [...]

In this work, a mixture of glycerol (Gly) and derivatives of pentaerythritol or α. α'-diglycerol is used as a plasticizer for preparing a thermoplastic starch (TPS). A coplasticizer containing both hydroxyl group and a long aliphatic chain was synthesized by esterification reaction between pentaerythritol or α. α'-diglycerol and palmi-toyl chloride in two different molar ratios, that is, 1:1 (PTI and DG1), 1:2 (PT2 and DG2). The esterification products were characterized using Fourier transform infrared spectroscopy, [.sup.1]H, and [.sup.13]C nuclear magnetic resonance spectroscopy. The starch and the mixed plasticizer were blended in an internal mixer. The morphology and miscibility of the blends were investigated by scanning electron microscope. The mechanical properties, moisture adsorption, and retrogradation phenomenon of the TPS specimens were studied. The results indicated that the TPS specimen containing a mixed plasticizer in a weight ratio of 80% Gly: 20% PT1 showed the highest values of Young's modulus and tensile strength, because this mixed plasticizer system could form stronger hydrogen bonds with starch molecules. Moreover, thermoplastic starch with higher content of pentaerythritol or α. α'-diglycerol derivatives as a coplas-ticizer showed lower moisture adsorption, because its long aliphatic chain (hydrophobic part) of pentaerythritol derivatives may prevent starch molecules to reform hydrogen bonding and to recrystallize. POLYM. ENG. SCI., 53:134-145, 2013. © 2012 Society of Plastics Engineers, INTRODUCTION The production and consumption of petrochemical-based plastics for various purposes in the last few decades have increased tremendously and generated enormous amount of plastic wastes, which are increasingly putting [...]