- Synthesis of chloroesters by the cleavage of cyclic and acyclic ethers using La(NO3)3·6H2O as a mild and efficient catalyst under solvent-free conditions
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A mild and an efficient synthesis of chloroesters is described by the reaction of cyclic and acyclic ethers with acid chlorides in the presence of a catalytic amount of La(NO3)3·6H2O under solvent-free conditions, affording the corresponding chloroesters in excellent yields. Copyright Taylor & Francis Group, LLC.
- Suresh,Suryakiran,Rajesh,Selvam, J. Jon Paul,Srinivasulu,Venkateswarlu
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- Practical and Selective sp3 C?H Bond Chlorination via Aminium Radicals
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The introduction of chlorine atoms into organic molecules is fundamental to the manufacture of industrial chemicals, the elaboration of advanced synthetic intermediates and also the fine-tuning of physicochemical and biological properties of drugs, agrochemicals and polymers. We report here a general and practical photochemical strategy enabling the site-selective chlorination of sp3 C?H bonds. This process exploits the ability of protonated N-chloroamines to serve as aminium radical precursors and also radical chlorinating agents. Upon photochemical initiation, an efficient radical-chain propagation is established allowing the functionalization of a broad range of substrates due to the large number of compatible functionalities. The ability to synergistically maximize both polar and steric effects in the H-atom transfer transition state through appropriate selection of the aminium radical has provided the highest known selectivity in radical sp3 C?H chlorination.
- McMillan, Alastair J.,Sieńkowska, Martyna,Di Lorenzo, Piero,Gransbury, Gemma K.,Chilton, Nicholas F.,Salamone, Michela,Ruffoni, Alessandro,Bietti, Massimo,Leonori, Daniele
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supporting information
p. 7132 - 7139
(2021/03/03)
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- Synthesis of an azide-tethered 4H-furo[3,4-b]indole
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We describe the synthesis of a novel azide-tethered 4H-furo[3,4-b]indole as a putative intermediate for a projected route to the 2-acylindole class of indole alkaloids. O N3 Me N N N H N H H O
- Keavy, Daniel J.,Liu, Yanbing,Gribble, Gordon W.
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p. 368 - 375
(2020/02/13)
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- Site-Selective Aliphatic C-H Chlorination Using N-Chloroamides Enables a Synthesis of Chlorolissoclimide
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Methods for the practical, intermolecular functionalization of aliphatic C-H bonds remain a paramount goal of organic synthesis. Free radical alkane chlorination is an important industrial process for the production of small molecule chloroalkanes from simple hydrocarbons, yet applications to fine chemical synthesis are rare. Herein, we report a site-selective chlorination of aliphatic C-H bonds using readily available N-chloroamides and apply this transformation to a synthesis of chlorolissoclimide, a potently cytotoxic labdane diterpenoid. These reactions deliver alkyl chlorides in useful chemical yields with substrate as the limiting reagent. Notably, this approach tolerates substrate unsaturation that normally poses major challenges in chemoselective, aliphatic C-H functionalization. The sterically and electronically dictated site selectivities of the C-H chlorination are among the most selective alkane functionalizations known, providing a unique tool for chemical synthesis. The short synthesis of chlorolissoclimide features a high yielding, gram-scale radical C-H chlorination of sclareolide and a three-step/two-pot process for the introduction of the β-hydroxysuccinimide that is salient to all the lissoclimides and haterumaimides. Preliminary assays indicate that chlorolissoclimide and analogues are moderately active against aggressive melanoma and prostate cancer cell lines.
- Quinn, Ryan K.,K?nst, Zef A.,Michalak, Sharon E.,Schmidt, Yvonne,Szklarski, Anne R.,Flores, Alex R.,Nam, Sangkil,Horne, David A.,Vanderwal, Christopher D.,Alexanian, Erik J.
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supporting information
p. 696 - 702
(2016/02/03)
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- An efficient iron catalyzed regioselective acylative cleavage of ethers: Scope and mechanism
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A method involving iron catalyzed acylative cleavage of cyclic and acyclic ethers with acyl/aroyl chlorides has been studied to produce chloroesters and esters respectively. Examination of the scope revealed that less electron rich alkyl group in unsymmetric, acyclic ether was acylated while the chloride derived from the counterpart moiety was volatile and difficult to isolate. In contrast, α-branched cyclic ethers were converted to the corresponding primary ester and secondary chloride. Steric hindrance of ether also plays an important role in acylative C-O bond cleavage. The mechanism of ether cleavage is proposed to involve a single electron initiated SN1 dissociative pathway.
- Bodduri, V.D. Vijaykumar,Choi, Kyung-Min,Vaidya, Raghavender Rao,Patil, Kalpesh,Chirumarry, Sridhar,Jang, Kiwan,Yoon, Yong-Jin,Falck, John R.,Shin, Dong-Soo
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supporting information
p. 7089 - 7093
(2015/12/01)
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- Heavier chalcogenone complexes of bismuth(iii)trihalides: Potential catalysts for acylative cleavage of cyclic ethers
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Heavier chalcogenones (S, Se and Te) of imidazole act as versatile ligands to yield a series of mononuclear and dinuclear bismuth(iii)complexes of heavier chalcogenones in excellent yield. These new bismuth heavier chalcogen derivatives are the first structurally characterized molecules, where the bismuth and heavier chalcogen ratio is 1:1. There is only one previous report of a crystal structure of a bismuth(iii)-imidazol selone compound and none with bismuth(iii)-imidazol tellone. The bismuth center in monomeric bismuth chalcogen trihalides depicts pseudo trigonal bipyramidal geometry, while the dimeric bismuth chalcogen trihalides demonstrate distorted square pyramidal geometry. The solid state structures of bismuth chalcogenone derivatives feature rare Bi...π(aryl) interactions. Thus, the centroid of the C6-ring suggests a half sandwich type of bismuth environment in mononuclear and dinuclear bismuth(iii) chalcogenone complexes. Notably, the Bi...π(aryl) interaction is not often noticed for mononuclear bismuth chalcogen compounds. Some of the bismuth(iii) chalcogenone complexes also exhibit C-H...π(aryl), C-H...S and C-H...Cl types of hydrogen bonding. The bismuth-chalcogen bond distance in mononuclear bismuth(iii)tribromide chalcogenone complexes is slightly longer than in mononuclear bismuth(iii)trichloride chalcogenone complexes. A gradual increase in carbon-chalcogen bond distance was observed from the free imidazole-chalcogenone to mononuclear bismuth(iii)trichloride chalcogenones, dinuclear bismuth(iii)trichloride chalcogenones and mononuclear bismuth(iii)tribromide chalcogenones and dinuclear bismuth(iii)tribromide chalcogenones. The UV-vis absorption properties and thermal decomposition properties of imidazol chalcogenones and their bismuth derivatives were investigated. Furthermore, the O-acylative cleavage of cyclic ethers was demonstrated using mononuclear and dinuclear bismuth(iii)complexes of heavier chalcogenones as catalysts. In contrast to bismuth(iii)trichloride and bismuth(iii)tribromide catalysts, mononuclear and dinuclear bismuth(iii)complexes of heavier chalcogenones are very active towards an acylative cleavage of cyclic ethers through a mild and regioselective strategy. In particular, mononuclear imidazolthione-bismuth(iii)trichloride is very active towards O-acylative cleavage of 2-methyl tetrahydrofuran. This journal is
- Srinivas, Katam,Suresh, Paladugu,Babu, Chatla Naga,Sathyanarayana, Arruri,Prabusankar, Ganesan
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p. 15579 - 15590
(2015/03/05)
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- Synthesis and reactivity of novel α,α,β- and α,α,δ-trichlorinated imines
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A variety of different N-(2,2,3-trichloropropylidene)amines, N-(2,2,3-trichlorobutylidene)amines, and N-(2,2,5-trichloropentylidene)amines were synthesized for the first time, and their reactivity with regard to hydride reagents was investigated. In this way, N-(2,2,5-trichloropentylidene)amines were evaluated as substrates for the synthesis of piperidines, and N-(2,2,3-trichloropropylidene)amines and N-(2,2,3-trichlorobutylidene)amines were reduced efficiently into the corresponding novel β,β,γ- trichloroamines by means of sodium cyanoborohydride in methanol in the presence of acetic acid. Furthermore, N-(2,2,3-trichloropropylidene)amines were transformed into 2-(chloromethyl)aziridines by lithium aluminium hydride in Et2O, and N-(2,2,5-trichloropentylidene)acetamide was used for the first time as a suitable substrate for the addition of oxygen, nitrogen, and sulfur nucleophiles in good yields. Georg Thieme Verlag Stuttgart.
- D'Hooghe, Matthias,De Meulenaer, Bruno,De Kimpe, Norbert
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scheme or table
p. 2437 - 2442
(2009/04/08)
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- A mild and efficient synthesis of chloroesters by the cleavage of cyclic and acyclic ethers using Bi(NO3)3·5H2O as a catalyst under solvent-free conditions
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A facile, efficient synthesis of chloroesters is described. The reaction of cyclic and acyclic ethers with acid chlorides in the presence of catalytic amounts of Bi(NO3)2·5H2O under solvent-free conditions yielded the corresponding chloroesters. Also, the catalyst can be recovered conveniently and reused efficiently for at least six times.
- Suresh,Suryakiran,Venkateswarlu
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p. 1037 - 1040
(2008/09/16)
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- Transformation of OH-adduct of 1-chloro-4-iodobutane into intra-molecular radical cation in neutral aqueous solution
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The iodine centered OH-adduct formed on reaction of OH radicals with 1-chloro-4-iodobutane in neutral aqueous solution transforms (k=5.4×105 s-1) to an intra-molecular radical cation (). The unfavorable structural conformation of solute radical cation generated on reaction of OH radicals with 1-chloro-5-iodopentane does not allow the transformation of OH-adduct into an intra-molecular radical and instead a dimer radical cation () is formed.
- Mohan, Hari,Maity,Chattopadhyay,Mittal
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p. 493 - 498
(2007/10/03)
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- An efficient Fischer indole synthesis of avitriptan, a potent 5-HT(1D) receptor agonist
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An efficient synthesis of antimigraine drug candidate avitriptan (1, BMS 180048) is reported. The key step is a two-phase Fischer indolization reaction between hydrazine 6 and 5-chlorovaler-aldehyde, 20, to give the chloropropylindole 35, which is susceptible to acid-catalyzed degradation under the reaction conditions required for its formation. Sequential coupling of 35 with piperazine, 26, and 4-chloro-5-methoxypyrimidine, 24, gives the title compound in 40-45% overall yield. Significant improvements in the syntheses of the known starting materials, hydrazine 6, 5- chlorovaleraldehyde, 20, and 4-chloro-5-methoxypyrimidine, 24, were also achieved.
- Brodfuehrer,Chen,Sattelberg T.R.,Smith,Reddy,Stark,Quinlan,Reid
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p. 9192 - 9202
(2007/10/03)
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- A versatile and convenient protocol for the stereocontrolled synthesis of olefinic insect pheromones
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A combination of the Horner-Emmons synthesis of alkyl 2,4-dienoates with their hydrogenation over complex L·Cr(CO)3 catalysts (L = 3CO or arene) provides a versatile, stereocontrolled and operationally simple approach to the (Z)-disubstituted, (Z)-trisubstituted, (E)-trisubstituted alkenes and skipped (Z,Z)-disubstituted diolefins with a homoallylic type of function. This protocol, sometimes supplemented by an enzymatic hydrolysis, was successfully applied to the synthesis of configurationally pure (gp ≥ 98%) pheromones of the furniture carpet beetle, dry bean beetle, rusty grain beetle, square-necked grain beetle and of a trail-following pheromone mimic for subterranean termites
- Vasil'ev, Andrei A.,Vlasyuk, Alexei L.,Gamalevich, Galina D.,Serebryakov, Edward P.
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p. 389 - 400
(2007/10/03)
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- Cobalt(II)chloride catalysed cleavage of ethers with acyl halides: Scope and mechanism
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Cobalt(II) chloride in acetonitrile catalyses the cleavage of a wide variety of ethers with acyl halides under mild conditions to give the corresponding esters in good yields. Acyclic aliphatic ethers are cleaved to the corresponding ester and chlorides whereas the cyclic aliphatic ethers give rise to the ω-chloroesters. The benzyl ethers can be converted to the corresponding esters along with the formation of benzyl chloride and benzyl acetamide. A comparative study for the cleavage of allyl and benzyl ether has revealed that benzyl ether can be selectively cleaved in presence of the allyl ethers. The oxiranes can be cleaved in highly regioselective manner to the corresponding-β-chloroesters. The vinyl ethers undergo sp2-hybridised carbon-oxygen bond cleavage under these conditions. Based on product analysis, a mechanism involving electron transfer followed by O-acylation and S(N)1 or S(N)2 attack by chloride-ion is discussed.
- Iqbal,Srivastava
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p. 3155 - 3170
(2007/10/02)
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- MECHANISMS OF FREE-RADICAL REACTIONS. XXIV. QUANTITATIVE DESCRIPTION OF THE POLAR EFFECTS OF SUBSTITUENTS ON THE KINETICS OF THE FREE-RADICAL CHLORINATION OF ALIPHATIC COMPOUNDS BY N-CHLOROPIPERIDINE
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The free-radical chlorination of 1-substituted alkanes with electron-withdrawing substituents by N-chloropiperidine in trifluoroacetic acid was studied by the method of competing reactions, and the relative rate constants were obtained for all positions of the substrates.The data on the position selectivity can be described satisfactorily by means of an electrostatic model of the polar effect of the substituent, calculated according to the Kirkwood-Westheimer equation.The obtained characteristics of the electrostatic effect can be successfully applied to calculation of the substrate selectivity and the intermolecular relative rate constants for all the positions, beginning with the third.The Taft equation is unsuitable for description of the effect of substituents on the reaction rate.
- Dneprovskii, A. S.,Mil'tsov, S. A.,Arbuzov, P. V.
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p. 1826 - 1835
(2007/10/02)
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- Experimental evidence for AcO-7 neighboring group participation
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The reaction of diol diacetates with anhydrous aluminium chloride at ca 100° leads to displacement of only one of the acetoxy groups by chlorine. An oxygen-18 label study has shown that these displacements take place via acetoxonium intermediates and has provided direct evidence for the intervention of a seven-membered ring acetoxonium ion in the displacement of acetate by chlorine in 1,4-butanediol diacetate.
- Wilen, Samuel H.,Delguzzo, Luciano,Saferstein, Richard
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p. 5089 - 5094
(2007/10/02)
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- N-Nitroso Sultams: On the Direction of Approach of Nucleophiles to the Sulfonyl Group
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The N-nitroso derivatives of propanesultam, butanesultam, and pentanesultam were synthesized along with N-nitropropanesultam and N-nitro-N-methylmethanesulfonamide.The decompositions of the N-nitroso sultams, wich increase in rate with increasing ring size, yield the corresponding sultones and also varying amounts of regenerated sultams.These reactions are discussed in terms of higher energy pathway involving approach of the nucleophile in a direction between of sulfonyl oxygens (on the O, O, N face) and a lower energy pathway involving the conformer which permits approach of the nucleophile trans to and colinear with one of the coordinate covalent oxygen atoms (on R, O, N face). The mechanisms of the decomposition of the N-nitro sulfonamides and the tosyloxy diimide N-oxides are also discussed.N-nitrosopropanesultam (and the butyl analoque) are potent inhibitors of proteinase α-chymotrypsin.
- White, Emil H.,Lim, Hyung M.
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p. 2162 - 2166
(2007/10/02)
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- Cobalt(II) Chloride Catalysed Acylative Cleavage of Ethers
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In the presence of catalytic amount of cobalt(II) chloride in acetonitrile, a wide variety of ethers are cleaved with acyl chlorides, to the corresponding esters in good to excellent yield.
- Ahmad, Saeed,Iqbal, Javed
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p. 953 - 956
(2007/10/02)
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- Novel omega-(N-imidazolyl)alkyl ethers of 1,2,3,5-tetrahydroimidazo[2,1-b]quinazolin-2-ones
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Novel compound wherein n is an integer of 1 to 8; R1 is hydrogen or alkyl of 1-6 carbons; R2 is hydrogen; R3 is hydrogen, alkyl of 1-6 carbons, phenyl, benzyl, hydroxy lower alkyl, carbamoyl alkyl, carboxyalkyl, alkoxycarbonylalkyl; R4 is hydrogen, alkyl of 1-6 carbons, benzyl, or hydroxy lower alkyl; Y is hydrogen, alkyl of 1 to 4 carbon atoms, halo or lower alkoxy; any of its optical isomers, the mixture thereof, or the pharmaceutically acceptable acid addition salt. These compounds are inhibitors of thromboxane synthetase and cyclic AMP phosphodiesterase and are therefore potential cardiovascular agents particularly useful as platelet aggregation inhibitors and anti-thrombotic agents. Accordingly, these compounds will preferably be useful in treating cardiovascular disorders with thrombotic complications. However, they also possess vasodilatory, antisecretory, antihypertensive, inotropic and antimetastatic activities.
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- Chlorination of Carboxylic Acid Derivatives. IX. Liquid Phase Chlorination of Aliphatic C2-C8 Alkyl Acetates. EI Mass Spectra of Monochlorinated Esters
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A series of aliphatic alkyl acetates from ethyl to octyl acetate was chlorinated in the liquid phase in order to obtain monochlorinated products.The chlorination of esters was carried out with chlorine in the liquid phase in the absence and in the presence of benzene and with sulfuryl chloride in the presence of Bz2O2.The products were determined by gas-liquid chromatography and gas-liquid chromatography-mass spectrometry.Chlorination is appreciably deactivated at the 1-position, particularly with SO2Cl2, the deactivation at the 2-position being strongest with Cl2 in the presence of benzene.The amounts of 1-chloro and ω-chloro isomers constituted the greatest disparity between the chlorination methods.The most characteristic mass spectral fragment ions of the 35 chlorinated alkyl acetates are given.
- Korhonen, Ilpo O. O.
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- 11,12-Secoprostaglandins
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This invention relates to 11,12-secoprostaglandins and processes for their manufacture. These compounds have prostaglandin-like biological activity and are particularly useful as renal vasodilators, for the treatment of hypertension, for the prevention of thrombus formation, in preventing gastric secretion, and as regulators of the immune response.
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- Preparation of haloalkyl esters
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Haloalkyl esters are prepared by reacting a saturated cyclic ether with a carboxylic acid or anhydride thereof and a hydrogen halide or hydrohalic acid in the presence of a Friedel-Crafts catalyst.
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- 8-Aza-9-oxo(and dioxo)-thia-11,12-secoprostaglandins
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This invention relates to 8-aza-9-oxo(and dioxo)-thia-11,12-secoprostaglandins and processes for their manufacture. These compounds have prostaglandin-like biological activity and are particularly useful as renal vasodilators, for the prevention of thrombus formation, to induce growth hormone release, and as regulators of the immune response.
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- 11,12-Secoprostaglandins
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This invention relates to 8-aza-11,12-secoprostaglandins and processes for their manufacture. These compounds have prostaglandin-like biological activity and are particularly useful as renal vasodilators.
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- 11,12-Secoprostaglandins
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This invention relates to 8,10-diaza-9-oxo(and thioxo)-11,12-secoprostaglandins and processes for their manufacture. These compounds have prostaglandin-like biological activity and are particularly useful as renal vasodilators, and for the prevention of thrombus formation.
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