- One-Pot Generation of Benzynes from Phenols: Formation of Primary Anilines by the Deoxyamination of Phenols
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Benzynes were selectively generated in situ from phenols and trapped regioselectively with potassium hexamethyldisilazide to form primary anilines following acidic workup. The direct conversion of a phenolic hydroxyl group into a free amino group is a useful method for the preparation of primary aryl amines that are hard to synthesize by using coupling reactions involving phenol derivatives with ammonia. Whereas reactions of ortho- and meta-substituted phenols produced meta-substituted anilines exclusively, those of para-substituted phenols provided ortho-silylanilines.
- Akai, Shuji,Ikawa, Takashi,Masuda, Shigeaki
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- Synthesis method of 5-(2-bromoacetyl)-2-hydroxybenzaldehyde
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The invention discloses a synthesis method of 5-(2-bromoacetyl)-2-hydroxybenzaldehyde, and belongs to the field of medicine synthesis. According to the method, the acylation reaction is conducted withsalicylaldehyde as the raw material to obtain 2-(acetoxyl)-benzaldehyde, then the rearrangement reaction is conducted, and finally the bromination reaction is conducted to obtain 5-(2-bromoacetyl)-2-hydroxybenzaldehyde. The preparing method has the advantages of being high in product purity and high in yield.
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Paragraph 0014; 0020
(2019/06/12)
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- The studies on chemoselective promiscuous activity of hydrolases on acylals transformations
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Chemoselective, mild and convenient protocol for the hydrolysis of the synthetically relevant acylals via promiscuous enzyme-catalyzed hydrolysis has been developed. It has been shown that promiscuous activity of the used hydrolases dominates their native activity related with carboxylic esters hydrolysis. The main advantage of the present methodology is that it can be conducted under neutral conditions at room temperature. Moreover, complete deprotection of acylals takes place within 10–20 min. Developed protocol can be used with compounds having a variety of hydrolytic labile groups since the cleavage is proceeded under neutral conditions and occurs exclusively on acylal moiety. Further this protocol was extended by the tandem Passerini multicomponent reaction leading to the α-acetoxy amides using acylals as the surrogates of the carbonyl components to P-MCR.
- Koszelewski, Dominik,Ostaszewski, Ryszard
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supporting information
(2019/02/27)
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- Generation of Phosphoranyl Radicals via Photoredox Catalysis Enables Voltage-Independent Activation of Strong C-O Bonds
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Despite the prevalence of alcohols and carboxylic acids as functional groups in organic molecules and the potential to serve as radical precursors, C-O bonds remain difficult to activate. We report a synthetic strategy for direct access to both alkyl and acyl radicals from these ubiquitous functional groups via photoredox catalysis. This method exploits the unique reactivity of phosphoranyl radicals, generated from a polar/SET crossover between a phosphine radical cation and an oxygen-centered nucleophile. We show the desired reactivity in the reduction of benzylic alcohols to the corresponding benzyl radicals with terminal H atom trapping to afford the deoxygenated products. Using the same method, we demonstrate access to synthetically versatile acyl radicals, which enables the reduction of aromatic and aliphatic carboxylic acids to the corresponding aldehydes with exceptional chemoselectivity. This protocol also transforms carboxylic acids to heterocycles and cyclic ketones via intramolecular acyl radical cyclizations to forge C-O, C-N, and C-C bonds in a single step.
- Stache, Erin E.,Ertel, Alyssa B.,Rovis, Tomislav,Doyle, Abigail G.
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p. 11134 - 11139
(2018/11/21)
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- (Z)-selective Takai olefination of salicylaldehydes
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The Takai olefination (or Takai reaction) is a method for the conversion of aldehydes to vinyl iodides, and has seen widespread implementation in organic synthesis. The reaction is usually noted for its high (E)-selectivity; however, herein we report the
- Geddis, Stephen M.,Hagerman, Caroline E.,Galloway, Warren R. J. D.,Sore, Hannah F.,Goodman, Jonathan M.,Spring, David R.
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supporting information
p. 323 - 328
(2017/03/14)
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- Selective reduction of carboxylic acids to aldehydes with hydrosilane: Via photoredox catalysis
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The direct reduction of carboxylic acids to aldehydes with hydrosilane was achieved through visible light photoredox catalysis. The combination of both single electron transfer and hydrogen atom transfer steps offers a novel and convenient approach to selective reduction of carboxylic acids to aldehydes. The method also features mild conditions, high yields, broad substrate scope, and good functional group tolerance, such as alkyne, ester, ketone, amide and amine groups.
- Zhang, Muliang,Li, Nan,Tao, Xingyu,Ruzi, Rehanguli,Yu, Shouyun,Zhu, Chengjian
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supporting information
p. 10228 - 10231
(2017/09/22)
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- Silver Tetrafluoroborate-Catalyzed Oxa-Diels-Alder Reaction between Electrically Neutral Dienes and Aldehydes
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Chemoselective oxa-Diels-Alder reactions between electrically neutral 1,3-dienes and various aldehydes were achieved using the commercially available silver tetrafluoroborate (AgBF4) as catalyst. This catalytic process has high functional group tolerance. Heteroatoms at the β-position of the aryl aldehydes can greatly promote the reactivity of the substrates even with heterocyclic aldehydes that were previously believed to be unreactive for the oxa-Diels-Alder reaction. In addition, acroleins with β-heteroatom substitution are also good substrates. High chemoselectivity and regioselectivity were achieved at room temperature for the oxa-Diels-Alder reaction between acroleins and stoichiometric simple 1,3-dienes.
- Zou, Xiaodong,Yang, Lizheng,Liu, Xiangli,Sun, Hao,Lu, Hongjian
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supporting information
p. 3040 - 3046
(2015/11/03)
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- Green procedures for the chemoselective synthesis of acylals and their cleavage promoted by recoverable sulfonic acid based nanoporous carbon (CMK-5-SO3H)
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A selective synthesis of gem-diacetates from the reaction of aldehydes and acetic anhydride in the presence of recyclable nanoporous solid sulfonic acid (CMK-5-SO3H) under solvent-free reaction conditions is reported. The catalyst was also found to be highly active for deprotection of resulting acylals in water. [Figure not available: see fulltext.]
- Zareyee, Daryoush,Mirzajanzadeh, Ehsan,Khalilzadeh, Mohammad Ali
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p. 1229 - 1234
(2015/10/06)
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- Effective synthesis of kynurenine-containing peptides via on-resin ozonolysis of tryptophan residues: Synthesis of cyclomontanin B
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The preparation of Kyn-containing peptides is difficult, owing to the low reactivity of Kyn in the coupling reaction. In this report, Kyn-containing peptides were efficiently obtained via on-resin ozonolysis of the corresponding Trp-containing peptide. In
- Wong, Clarence T. T.,Lam, Hiu Yung,Li, Xuechen
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supporting information
p. 7616 - 7620
(2013/11/06)
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- Synthesis of constrained head-to-tail cyclic tetrapeptides by an imine-induced ring-closing/contraction strategy
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Making heads or tails of it: A strategy involving a head-to-tail imine-captured ring closure followed by ring contraction was used to synthesize otherwise difficult cyclic tetrapeptides. Compared with the direct lactamization process, the estimated activa
- Wong, Clarence T. T.,Lam, Hiu Yung,Song, Tao,Chen, Guanhua,Li, Xuechen
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supporting information
p. 10212 - 10215
(2013/10/21)
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- Copper(I)-catalyzed hydroalkoxylation/hydrogen-bonding-induced asymmetric hetero-diels-alder cycloaddition cascade: An approach to aromatic spiroketals
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One thing leads to another: Bis(benzannelated) 5,6-spiroketal skeletons can be constructed by an efficient cascade process involving an unprecedented CuI-catalyzed intramolecular alkyne hydroalkoxylation and an asymmetric hetero-Diels-Alder cyc
- Li, Xin,Xue, Jijun,Huang, Chusheng,Li, Ying
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supporting information; experimental part
p. 903 - 906
(2012/07/03)
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- A synthesized GFP analogue emits via a hydrogen-bonding system
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Two GFP analogues o-HBDI and o-HBMO have been designed and synthesized. The former shows no fluorescence while the latter shows strong fluorescence due to the formation of an intramolecular hydrogen-bond. At low temperatures, both molecules have strong fl
- Kang, Juntao,Zhao, Guiyan,Xu, Jingwei,Yang, Wei
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supporting information; experimental part
p. 2868 - 2870
(2010/09/04)
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- Controlled and chemoselective reduction of secondary amides
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This communication describes a metal-free methodology involving an efficient and controlled reduction of secondary amides to imines, aldehydes, and amines in good to excellent yields under ambient pressure and temperature. The process includes a chemoselective activation of a secondary amide with triflic anhydride in the presence of 2-fluoropyridine. The electrophilic activated amide can then be reduced to the corresponding iminium using triethylsilane, a cheap, rather inert, and commercially available reagent. Imines can be isolated after a basic workup or readily transformed to the aldehydes following an acidic workup. The amine moiety can be accessed via a sequential reductive amination by the addition of silane and Hantzsch ester hydride in a one-pot reaction. Moreover, this reduction tolerates various functional groups that are usually reactive under reductive conditions and is very selective to secondary amides.
- Pelletier, Guillaume,Bechara, William S.,Charette, Andre B.
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supporting information; experimental part
p. 12817 - 12819
(2010/11/05)
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- Synthesis and evaluation in monkey of two sensitive 11C-labeled aryloxyanilide ligands for imaging brain peripheral benzodiazepine receptors in vivo
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We sought to develop 11C-labeled ligands for sensitive imaging of brain peripheral benzodiazepine receptors (PBR) in vivo. Two aryloxyanilides with high affinity for PBR were identified and synthesized, namely, N-acetyl-N-(2-methoxycarbonylbenzyl)-2-phenoxyaniline (3, PBR01) and N-(2-methoxybenzyl)-N-(4-phenoxypyridin-3-yl)acetamide (10, PBR28). 3 was hydrolyzed to 4, which was esterified with [11C]iodomethane to provide [11C]3. The O-desmethyl analogue of 10 was converted into [11C]10 with [11C]iodomethane. [11C]3 and [11C]10 were each injected into monkey to assess their brain kinetics with positron emission tomography (PET). After administration of either radioligand there was moderately high brain uptake of radioactivity. Receptor blocking and displacement experiments showed that a high proportion of this radioactivity was bound specifically to PBR. In monkey and rat, 3 and 10 were rapidly metabolized by ester hydrolysis and N-debenzylation, respectively, each to a single polar radiometabolite. [11C]3 and [11C]10 are effective for imaging PBR in monkey brain. [11C]10 especially warrants further evaluation in human subjects.
- Briard, Emmanuelle,Zoghbi, Sami S.,Imaizumi, Masao,Gourley, Jonathan P.,Shetty, H. Umesha,Hong, Jinsoo,Cropley, Vanessa,Fujita, Masahiro,Innis, Robert B.,Pike, Victor W.
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- Alcohol uncaging with fluorescence reporting: Evaluation of o-acetoxyphenyl methyloxazolone precursors
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(Chemical Equation Presented) This paper evaluates a series of photolabile protecting groups with built-in fluorescence reporting. They rely on readily available o-acetoxyphenyl methyloxazolones as activated precursors. Alcohol substrates are easily caged. The resulting photoactivable esters exhibit large one- and two-photon uncaging cross sections. The alcohol substrates are quantitatively released in a 1:1 molar ratio with a strongly fluorescent coumarin coproduct that serves as a reporter to quantify substrate delivery.
- Gagey, Nathalie,Emond, Matthieu,Neveu, Pierre,Benbrahim, Chouaha,Goetz, Bernard,Aujard, Isabelle,Baudin, Jean-Bernard,Jullien, Ludovic
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supporting information; experimental part
p. 2341 - 2344
(2009/06/06)
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- Mild and selective hydrozirconation of amides to aldehydes using Cp 2Zr(H)Cl: Scope and mechanistic insight
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An investigation of the use of Cp2Zr(H)Cl (Schwartz's reagent) to reduce a variety of amides to the corresponding aldehydes under very mild reaction conditions and in high yields is reported. A range of tertiary amides, including Weinreb's amides, can be converted directly to the corresponding aldehydes with remarkable chemoselectivity. Primary and secondary amides proved to be viable substrates for reduction as well, although the yields were somewhat diminished as compared to the corresponding tertiary amides. Results from NMR experiments suggested the presence of a stable, 18-electron zirconacycle intermediate that presumably affords the aldehyde upon water or silica gel workup. A series of competition experiments revealed a preference of the reagent for substrates in which the lone pair of the nitrogen is electron releasing and thus more delocalized across the amide bond by resonance. This trend accounts for the observed excellent selectivity for tertiary amides versus esters. Experiments regarding the solvent dependence of the reaction suggested a kinetic profile similar to that postulated for the hydrozirconation of alkenes and alkynes. Addition of p-anisidine to the reaction intermediate resulted in the formation of the corresponding imine mimicking the addition of water that forms the aldehyde.
- Spletstoser, Jared T.,White, Jonathan M.,Tunoori, Ashok Rao,Georg, Gunda I.
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p. 3408 - 3419
(2007/10/03)
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- Silver-catalyzed asymmetric synthesis of 2,3-dihydrobenzofurans: A new chiral synthesis of pterocarpans
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2,3-Dihydrobenzofurans can be diastereoselectively prepared by condensation of aromatic aldehydes with 2,3-dihydrobenzoxasilepines under the catalysis of Ag1 complexes, and in the presence of a source of fluoride ion. The application of this st
- Jimenez-Gonzalez, Leticia,Garcia-Munoz, Sergio,Alvarez-Corral, Miriam,Munoz-Dorado, Manuel,Rodriguez-Garcia, Ignacio
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p. 8762 - 8769
(2007/10/03)
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- Expeditious synthesis of the aromatic spiroketal skeleton using hetero-Diels-Alder cycloaddition
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The hetero-Diels-Alder reactions of enolic ethers generated from methylenation of various esters are described, which allow for the rapid synthesis of various substituted [6,6] aromatic spiroketal skeletons.
- Zhou, Guanglian,Zheng, Deping,Da, Shijun,Xie, Zhixiang,Li, Ying
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p. 3349 - 3352
(2007/10/03)
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- Solid-state conversion of 1,1-diacetates with N,N′-dibromo-N, N′-1,2-ethanediylbis(p-toluenesulfonamide) to aldehydes
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N,N′-Dibromo-N,N′-1,2-ethanediylbis(p-toluenesulfonamide) can be used for the solid-state conversion of 1,1-diacetates to aldehydes in excellent yields.
- Ghorbani-Vaghei, Ramin,Akbari, Safar-Ali,Zolfigol, Mohammad A.,Mirjalili, BiBi Fatemeh,Bamoniri, Abdolhamid
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- Mild and eco-friendly oxidative cleavage of 1,3-dithianes and 1,3-dithiolanes with a catalytic amount of hydrobromic acid and hydrogen peroxide: Synergetic effect of bromonium ion equivalent and hydrogen peroxide
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A combination of a catalytic amount hydrobromic acid (10 mol%) and an excess of hydrogen peroxide is found to be an effective reagent for expeditious regeneration of carbonyl compounds from their 1,3-dithiane as well as 1,3-dithiolane derivatives. Absence of nuclear bromination of aromatic substrates and overoxidation of regenerated oxidation-prone aromatic aldehydes, compatibility with a number of functional groups, such as amino, hydroxy, acetoxy, methylenedioxy and useful phenol-protecting allyl, benzyl and TBDMS ethers, benzoate esters and amino-protecting Cbz carbamate and N-benzylamine (NHBn) moieties are the advantageous features of this protocol.
- Ganguly, Nemai C.,Datta, Mrityunjoy
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p. 218 - 221
(2007/10/03)
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- A rapid and efficient procedure for deprotection of 1,1-diacetates catalysed by silica sulfate
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An efficient procedure for converting a number of 1,1-diacetates into the corresponding aldehydes was developed with silica sulfate as catalyst. The advantages of this procedure is its brevity, and high yield. It is environmentally friendly and the catalyst is also inexpensive and reusable.
- Jin, Tong-Shou,Zhao, Ying,Liu, Li-Bin,Li, Tong-Shuang
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p. 438 - 439
(2007/10/03)
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- Ecofriendly solid-state oxidative deprotection of 1,3-dithianes and 1,3-dithiolanes using ammonium persulfate on wet montmorillonite K-10 clay support under microwave irradiation
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Solid-state microwave-assisted oxidative deprotection of 1,3-dithianes and 1,3-dithiolanes of aromatic aldehydes and ketones, cyclic ketones, α,β-unsaturated aldehydes and aliphatic aldehydes and ketones has been accomplished using ammonium persulfate on wet montmorillonite K-10 clay support.
- Ganguly, Nemai C.,Datta, Mrityunjoy
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p. 659 - 662
(2007/10/03)
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- Efficient and chemoselective deprotection of 1,1-diacetates using Fe 2(SO4)3·xH2O as a heterogeneous catalyst
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Various substituted 1,1-diacetates are smoothly transformed to the corresponding aldehydes by using hydrated ferric sulfate as heterogeneous catalyst at reflux in dichloroethane. The advantages of this methodology are: high yields, good chemoselectivity, inexpensive and environmentally benign catalyst as well as short reaction time and operational simplicity.
- Li, Lingjun,Zhang, Xinying,Zhang, Guisheng,Qu, Guirong
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- Study of different substituted cyclic and acyclic benzylpronucleotides of d4T relative to their hydrolytic stability and antiviral activity
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CycloSal-d4TMP and two different bis(benzyl) phosphate triesters of the antivirally active nucleoside analog d4T were studied with regard to their chemical hydrolysis behavior at pH 7.3, in CEM/0 cell extracts, and their anti-HIV activity. In contrast to
- Muus,De Clercq,Balzarini,Naesens,Meier
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p. 791 - 795
(2007/10/03)
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- Convenient synthesis of a simple coumarin from salicylaldehyde and wittig reagent. IV: Improved synthetic method of substituted coumarins
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The reaction of salicylaldehydes (2) with Horner-Wadsworth-Emmons (HWE) or Ando-HWE reagents was attempted to afford intramolecular phosphonate derivatives (6). A new synthetic method for coumarins (1) was achieved by using protected 2.
- Takeuchi, Yasuo,Ueda, Norihiro,Uesugi, Koji,Abe, Hitoshi,Nishioka, Hiromi,Harayama, Takashi
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p. 217 - 224
(2007/10/03)
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- A facile and efficient procedure for deprotection of 1,1-diacetates catalysed by H2NSO3H
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A rapid, efficient and high yield method of the deprotection of 1,1-diacetates is described which occurs under catalysis of H2NSO3H.
- Jin, Tong-Shou,Sun, Guang,Li, Yan-Wei,Li, Tong-Shuang
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- New applications of solid silica chloride (SiO2-Cl) in organic synthesis. Efficient preparation of diacetals of 2,2-bis(hydroxymethyl)-1,3-propanediol from different substrates and their transthioacetalization reactions. Efficient regeneration of carbonyl compounds from acetals and acylals
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A new application of solid silica chloride, an easily available and efficient catalyst for the preparation of diacetal of 2,2-bis-(hydroxymethyl)-1,3-propanediol from aldehydes, acetals, acylals, and oximes, is described. Transthioacetalization of diacetals of 2,2-bis-(hydroxymethyl)-1,3-propanediol into their corresponding 1,3-dithianes and 1,3-dithiolanes in the presence of silica chloride is presented. Efficient regeneration of carbonyl compounds from their corresponding acetals, ketals, diacetals, and acylals in the presence of this catalyst also is described.
- Firouzabadi, Habib,Iranpoor, Nasser,Hazarkhani, Hassan
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p. 2847 - 2858
(2007/10/03)
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- Oxidative cleavage of diethyldithioacetals by ammonium bromide promoted by (NH4)6Mo7O24.4H2O-H 2O2: A useful synthetic protocol for regeneration of carbonyl compounds
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Ammonium heptamolybdate promotes selective deprotection of a wide variety of diethyldithioacetals of aldehydes or ketones 1 into the parent carbonyl compounds 2, by ammonium bromide in presence of hydrogen peroxide and catalytic amount of perchloric acid at 0-5 °C in dichloromethane-water solvent system; mild conditions, high selectivity, good yield and easy work-up are some of the major advantages of the synthetic method.
- Khan,Boruwa,Mondal,Bose
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p. 1039 - 1042
(2007/10/03)
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- A mild and efficient cleavage of gem-Diacetates to aldehydes by CBr4
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gem-Diacetates are selectively deprotected to the corresponding aldehydes in high yields by CBr4 in refluxing acetonitrile under neutral reaction conditions.
- Ramalingam,Srinivas,Subba Reddy,Yadav
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p. 1091 - 1095
(2007/10/03)
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- Efficient one-pot formation of amides from benzyl carbamates: Application to solid-phase synthesis
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A convenient one-pot protocol for the conversion of benzyl carbamates to amides is described. The general applicability of the procedure is illustrated using various types of substrates. This new method proceeds rapidly under mild conditions, in good yields, and without noticeable racemization. This protocol was applied to solid-phase synthesis to prepare amides and esters from Merrifield resin-bound carbamates and carbonates. (C) 2000 Elsevier Science Ltd.
- Li, Wen-Ren,Yo, Ying-Chih,Lin, Yu-Sheng
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p. 8867 - 8875
(2007/10/03)
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- Bismuth (III) chlorides; an efficient and selective catalyst for deprotection of 1,1-diacetates
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A variety of 1,1-diacetates are easily and efficiently deprotected in the presence of catalytic amounts of bismuth(III) chloride affording the corresponding aldehydes in high yields.
- Mohammadpoor-Baltork,Aliyan
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p. 2741 - 2746
(2007/10/03)
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- Aluminium chloride: A mild and efficient catalyst for selective deprotection of 1,1-diacetates
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A mild, efficient and excellent yield method for the selective deprotection of 1,1-diacetates to the corresponding aldehydes in the presence of aluminium chloride (AlCl3) is described.
- Mohammadpoor-Baltork, Iraj,Aliyan, Hamid
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p. 272 - 273
(2007/10/03)
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- Efficient and selective deprotection of aryl aldehyde diacetates catalyzed by tin(II) chloride dihydrate
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A mild, efficient and excellent yield method for the selective deprotection of aryl aldehyde diacetates in the presence of phenolic acetate and aliphatic aldehyde diacetate using catalytic amounts of tin(II) chloride dihydrate (SnCl2.2H2O) is described.
- Mohammadpoor-Baltork,Aliyan
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p. 1223 - 1225
(2007/10/03)
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- Montmorillonite clay catalysis V1: An efficient and facile procedure for deprotection of 1,1-diacetates
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A variety of 1,1-diacetates are easily deprotected in good to excellent yield under catalysis by montmorillonite clays in refluxing dichloromethane or benzene.
- Li, Tong-Shuang,Zhang, Zhan-Hui,Fu, Cheng-Guang
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p. 3285 - 3288
(2007/10/03)
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- Synthesis of tetra- and octahydroxanthene derivatives by the condensation of dimedone with aromatic aldehydes
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The reaction of dimedone with salicyl and 2-hydroxy-1-naphthoyl aldehydes gave derivatives of tetrahydroxanthene and tetrahydrobenzo[a]xanthene and not aldimedone as occurs in condensations with other aldehydes. Derivatives of decahydroacridine were obtained by reaction of the tetrahydroxanthene derivatives with methyl-and ethylamine. Tetrahydro- and octahydroxanthene derivatives were obtained from the reaction of acetylsalicylaldehyde with dimedone in acetic anhydride. The structures of the ketoenol forms of the products containing a β-ketoenol unit were determined by 1H and 13C NMR spectroscopy, and the mechanism of their interconversion is discussed. 1997 Plenum Publishing Corporation.
- Pyrko
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p. 635 - 645
(2007/10/03)
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- Dabco-catalysed reactions of salicylaldehydes with acrylate derivatives
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Treatment of salicylaldehydes with acrylate derivatives in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) has been shown to afford both coumarin and chromene derivatives, and factors influencing the product distributions have been investigated.
- Kaye, Perry T.,Robinson, Ross S.
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p. 2085 - 2097
(2007/10/03)
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- Cobalt(II)-Catalyzed Reaction of Aldehydes with Acetic Anhydride under an Oxygen Atmosphere: Scope and Mechanism
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The reaction of aldehydes with acetic anhydride in the presence of catalytic cobalt(II) chloride under an oxygen atmosphere at ambient temperature is dependent upon the reaction medium.Aliphatic aldehydes react in acetonitrile to give 1,2-diones whereas the aromatic aldehydes are acylated to yield the corresponding acylals.On the other hand, carboxylic acids are obtained from aliphatic and aromatic aldehydes by conducting the reaction in dichloroethane or benzene.Cobalt(II) chloride in acetonitrile catalyzes the conversion of aliphatic aldehydes to the correspondinganhydrides in the absence of acetic anhydride whereas aromatic aldehydes remain largely unaffected under these conditions.A preliminary mechanistic study in three different solvents (i.e. acetonitrile, dichloroethane, and DMF) has revealed that in acetonitrile and in the presence of acetic anhydride, aliphatic aldehydes behave differently than aromatic aldehydes.Some trapping experiments using methyl acrylate and stilbene have been conducted to demonstrate the occurence of an acyl cobalt and peroxyacyl cobalt intermediate during these reactions.
- Bhatia, Beena,Punniyamurthy, T.,Iqbal, Javed
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p. 5518 - 5523
(2007/10/02)
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- Methyl α-arylacrylates substituted by a heterocyclic radical and their use
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Methyl α-arylacrylates substituted by a heterocyclic radical and having the general formula STR1 where R is alkyl, alkenyl, haloalkyl, cycloalkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, halogen or aryl, the aromatic ring being unsubstituted or substituted, Het is a five-membered heteroaromatic ring which is unsubstituted or substituted and has from one to three heteroatoms, and A is ethenylene, ethylene, methyleneoxy or methylenethio, and fungicides and pesticides containing these compounds.
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- Titanium-Induced Syntheses of Furans, Benzofurans and Indoles
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Highly reactive titanium on graphite as the reagent of choice promotes intramolecular McMurry type reactions of acyloxy- and acylamido carbonyl compounds affording furans, benzofurans and indoles in good to excellent yields.A variety of reducible groups in the substrates is tolerated (e.g. -F, -Cl, -Br, -I, -CF3, -OMe, -CN, -thiophenyl, -COOR, -CONR2) and strained products such as 11h can be obtained, the X-ray analysis of which is reported.The experimental results indicate the possible formation of dianions from the aromatic aldehydes or ketones as reactive intermediates which attack the ester or amide functions in their proximity, rather than a radical path via ketyls.
- Fuerstner, Alois,Jumbam, Denis N.
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p. 5991 - 6010
(2007/10/02)
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- 4-(2'-Hydroxyphenylmethylene)-2-phenyloxyzol-5(4H)-one: A Comedy of Errors
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Eighteen publications since 1955 have described properties and reactions of the title compound.All these reports are erroneous and refer, variously, to three other substances.All literature reports of the analogous 4-(2'-hydroxyphenylmethylene)-2-methyloxazol-5(4H)-one also need revision.A convenient synthesis of the title compound 3 (R=H), its chemical and physical properties, and its rearrangement to 3-benzoylamino-1-benzopyran-2-one 1, are reported here for the first time.A mechanism is presented for the observed course of Ploechl-Erlenmeyer syntheses with salicylaldehyde and with 2-acetoxybenzaldehyde.
- Cornforth, Sir John,Ming-hui, Du
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p. 2183 - 2187
(2007/10/02)
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- Ortho Effect in the Fragmentation of 2-Acetoxychalcones under Electron Impact
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2-Acetoxychalcones decompose under electron impact conditions by loss of an acetoxy fragment to form flavylium ions.The effect is restricted to the ortho position and is reduced after hydrogenation of the chalcone double bond.The intense flavylium ion originates as shown by specific labelling with 18O-from two different fragmentation lines: (a) direct loss of an acetoxy radical by cleavage of the phenolic Ar-O bond and (b) sequential elimination of ketene and a hydroxy radical.
- Mentlein, Rolf,Vowinkel, Erich
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p. 330 - 333
(2007/10/02)
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- PHOTOLYSIS OF 2-ARYLOXY- OR 2-ARYLTHIO-1,3-BENZODIOXAN-4-ONES
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Photolysis of 1,3-benzodioxan-4-ones 3b and 4a gives mainly products derived from photorearrangement, photoreduction and/or photosolvolysis.These results closely parallel those obtained by irradiation of the isomeric open-chain compounds 1b and 2a.A mechanism involving the intermediacy of radical pairs A and B, generated by successive homolysis of the aryloxy- or arylthio-carbon and carbonyl-oxygen bonds, is proposed.
- Diaz-Mondejar, M. Rosa,Miranda, Miguel A.
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p. 1125 - 1131
(2007/10/02)
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- Novel uracil derivatives, process for preparing the same and a pharmaceutical composition containing the same
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Novel uracil derivatives of the formula STR1 (wherein R1, R2 R3 and X are defined in the description) and their pharmaceutically acceptable salts, process for preparing the same and pharmaceutical composition containing the same are disclosed. The uracil derivatives have good antitumor activity and, therefore, are useful as antitumor preparation.
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