- Continuous ion-exchange resin catalysed esterification of eugenol for the optimized production of eugenyl acetate using a packed bed microreactor
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A green scalable flow-synthesis process for the production of eugenyl acetate, an eugenol derivative with potential applications in food and medicinal chemistry, was developed. Through batch experiments, the anion-exchange resin Amberlyst A-21 was recognized as a suitable catalyst for the esterification of eugenol with acetic anhydride. Next, the process was switched from batch- to flow-mode by using a packed-bed microreactor integrated in an instrumental platform that permitted at the same time continuous control of the main process parameters (flow rate, feed mixture composition, temperature) and the on-line HPLC analysis of the reactor effluent. Thanks to this apparatus, a number of experiments with different reaction conditions have been easily performed to evaluate the effects of temperature and reagent molar ratios on eugenyl acetate production. The results have been used to carry out a central composite rotatable experimental design (CCRD) whose derived response surface model (RSM) suggested an optimal temperature and acetic anhydride to eugenol molar ratio of 95 °C and 3:1, respectively. The goodness of these theoretically deduced parameters has been experimentally confirmed obtaining, with a flow rate of 40 μL min-1, a 95% conversion. The Amberlyst A-21 packed-bed microreactor also demonstrated good long-term stability ensuring, under the above optimized conditions, a high and stable conversion (over 93%) for prolonged reaction times.
- Lerin,Catani,Oliveira,Massi,Bortolini,Cavazzini,Giovannini
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Read Online
- Synthesis of 5-Hydroxy-4-methoxy-α-methyl-(1,2-benzobutane sultone) from eugenol and eugenil acetate
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The purpose of this study was to develop an efficient synthesis route to pharmacologically interesting sultone derivatives from readily accessed natural products. Synthetic approach of 5-hydroxy-4-methoxy-α-methyl-(1,2-benzobutane sultone) via eugenol (1) produced only in moderate yield (64 %). On the other hand synthetic approach via eugenil acetate (2) gave 5-hydroxy-4-methoxy-α-methyl-(1,2-benzobutane sultone) in high yield (96 %). Eugenol approach involved only one step reaction due to direct reaction of eugenol with chlorosulfonic acid but in eugenil acetate approach involved two-step reactions due to its preparation of eugenol before reaction with chlorosulfonic acid. Eugenil acetate was prepared smoothly in good yield by esterification of phenolic group of eugenol with acetic anhydride in the presence of sodium bicarbonate. A variety of bicarbonate catalysts such as NaHCO3, Na2CO3 and K2CO3 were investigated in O-acetylation of eugenol to afford eugenil acetate (84 %), (72 %) and (88 %), respectively. Structures of all the products have been established by spectral and GC-MS analysis data.
- Sudarma,Supiani,Syafitri,Hidayati,Oltantia,Darmayanti
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Read Online
- Synthesis of eugenyl acetate by enzymatic reactions in supercritical carbon dioxide
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Supercritical carbon dioxide (SC-CO2) as reaction medium has gained attention in the production of terpenic esters catalyzed by lipases. Therefore, this work investigated the production of eugenyl acetate by esterification of eugenol and acetic anhydride in SC-CO2 using two commercial lipases (Lipozyme 435 and Novozym 435) as catalysts. The influence of enzyme concentration (1–10% weight/weight), substrates’ molar ratio (1:1 to 5:1), temperature (40–60?°C) and pressure of SC-CO2 (10–30?MPa) on the esterification rate (X; %) and specific productivity (SP; kg of product/kg of catalyst x hour) were evaluated. A home-made high-pressure stirred-batch reactor (100?ml) was used in the experiments. The use of Novozym 435 achieved higher conversion and specific productivity of eugenyl acetate than Lipozyme 435. An excess of acetic anhydride (5:1?M/M) and high enzyme concentration (10%) achieved higher esterification rates than the lowest conditions (1% and 1:1?M/M). The optimal temperatures and pressure for the synthesis of eugenyl acetate in SC-CO2 were 50 and 60?°C at 10?MPa, respectively. The phase behavior of the reaction system and the synthesis in organic medium were also studied. Kinetic experiments performed at 40, 50 and 60?°C indicated that the reaction follows the simple Ping-Pong Bi-Bi mechanism and the affinity of acetic anhydride to enzyme was larger than that of eugenol.
- dos Santos, Philipe,Zabot, Giovani L.,Meireles, M. Angela A.,Mazutti, Marcio A.,Martínez, Julian
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Read Online
- One-pot hydroformylation/O-acylation of propenylbenzenes for the synthesis of polyfunctionalized fragrances
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A process involving the hydroformylation/O-acylation of propenylbenzenes with a phenolic group is described for eugenol, isoeugenol, chavicol, propenyl guaethol, 2-allylphenol, and 2-allyl-6-methylphenol. The reactions occur in parallel, under the same reaction conditions in anisole, a solvent with an impressive sustainability rank comparable to those of ethanol and water. The products contain formyl and acetoxy moieties, both established olfactory groups in flavor and fragrance industry, and present potential as new fragrance components with less allergenic properties. To the best of our knowledge, this is the first time that a one-pot process involving hydroformylation combined with further functionalization in a remote site is described.
- Delolo, Fábio G.,Vieira, Gabriel M.,Villarreal, Jesus A.A.,dos Santos, Eduardo N.,Gusevskaya, Elena V.
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p. 272 - 279
(2020/06/17)
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- Biotechnological Potential of Eugenol and Thymol Derivatives Against Staphylococcus aureus from Bovine Mastitis
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Bovine mastitis is an infectious disease that affects the mammary gland of dairy cattle with considerable economic losses. Staphylococcus aureus is the main microorganism involved in this highly contagious process, and the treatment is only using antibiotics. Currently, the search for new treatment and/or compounds is still in need due to microbial resistance. In this work, we evaluated the potential of eugenol and thymol derivatives against S. aureus strains from bovine mastitis. On that purpose, nine derivatives were synthesized from eugenol and thymol (1–9), and tested against 15 strains of S. aureus from subclinical bovine mastitis. Initially, the strains were evaluated for the biofilm production profile, and those with strong adherence were selected to the antimicrobial sensitivity determination in the Minimum Inhibitory Concentration (MIC) assays. Herein the compounds toxicity was also evaluated by in silico analysis using Osiris DataWarrior software. The results showed that 60% of the strains were considered strongly adherent and three strains (S. aureus 4271, 4745 and 4746) were selected for the MIC tests. Among the nine eugenol and thymol derivatives tested, four were active against the evaluated strains (MIC = 32?μg?mL?1) within CLSI standard values. In silico analysis showed that all derivatives had cLopP ??4 and TPSA 140 ?2, and similar theoretical toxicity parameters to some antibiotics currently on the market. These molecules also showed negative drug-likeness values, pointing to the originality of these structures and theoretical feasibility on escaping of resistance mechanism and act against resistant strains. Thus, these eugenol derivatives may be considered as promising for the development of new treatments against bovine mastitis and future exploring on this purpose.
- Nunes, Daiana O. S.,Vinturelle, Rafaelle,Martins, Francislene J.,dos Santos, Thiago F.,Valverde, Alessandra Leda,Ribeiro, Carlos Magno R.,Castro, Helena C.,Folly, Evelize
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p. 1846 - 1855
(2021/04/29)
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- KMnO4-catalyzed chemoselective deprotection of acetate and controllable deacetylation-oxidation in one pot
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A novel and efficient protocol for chemoselective deacetylation under ambient conditions was developed using catalytic KMnO4. The stoichiometric use of KMnO4 highlighted the dual role of a heterogeneous oxidant enabling direct access to aromatic aldehydes in one-pot sequential deacetylation-oxidation. The reaction employed an alternative solvent system and allowed the clean transformation of benzyl acetate to sensitive aldehyde in a single step while preventing over-oxidation to acids. Use of inexpensive and readily accessible KMnO4 as an environmentally benign reagent and the ease of the reaction operation were particularly attractive, and enabled the controlled oxidation and facile cleavage of acetate in a preceding step. This journal is
- Gurawa, Aakanksha,Kumar, Manoj,Rao, Dodla S.,Kashyap, Sudhir
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supporting information
p. 16702 - 16707
(2020/10/27)
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- Scalable green approach toward fragrant acetates
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The advantageous properties of ethylene glycol diacetate (EGDA) qualify it as a useful substitute for glycerol triacetate (GTA) for various green applications. We scrutinised the lipase-mediated acetylation of structurally diverse alcohols in neat EGDA furnishing the range of naturally occurring fragrant acetates. We found that such enzymatic system exhibits high reactivity and selectivity towards activated (homo) allylic and non-activated primary/secondary alcohols. This feature was utilised in the scalable multigram synthesis of fragrant (Z)-hex-3-en-1-yl acetate in 70percent yield. In addition, the Lipozyme 435/EGDA system was also found to be applicable for the chemo-selective acetylation of (hydroxyalkyl) phenols as well as for the kinetic resolution of chiral secondary alcohols. Lastly, its discrimination power was demonstrated in competitive experiments of equimolar mixtures of two isomeric alcohols. This enabled the practical synthesis of 1-pentyl acetate isolated as a single product in 68percent yield from the equimolar mixture of 1-pentanol and 3-pentanol.
- Puchl'Ová, Eva,Szolcsányi, Peter
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- Synthesis of eugenol derivatives and its anti-inflammatory activity against skin inflammation
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Eugenol is a phytochemical present in aromatic plants has generated considerable interest in the pharmaceutical industries mainly in cosmetics. A series of eugenol esters (ST1-ST7) and chloro eugenol (ST8) have been synthesized. The structures of newly synthesized compounds were confirmed by 1H and 13C NMR and mass spectrometry. In an effort to evaluate the pharmacological activity of eugenol derivatives, we explored its anti-inflammatory potential against skin inflammation using in-vitro and in-vivo bioassay. Synthesized derivatives significantly inhibited the production of pro-inflammatory cytokines against LPS-induced inflammation in macrophages. Among all derivatives, ST8 [Chloroeugenol (6-chloro, 2-methoxy-4-(prop-2-en-1-yl)-phenol)] exhibited most potent anti-inflammatory activity without any cytotoxic effect. We have further evaluated the efficacy and safety in in-vivo condition. ST8 exhibited significant anti-inflammatory activity against TPA-induced skin inflammation without any skin irritation effect on experimental animals. These findings suggested that ST8 may be a useful therapeutic candidate for the treatment of skin inflammation.
- Agarwal, Karishma,Ahmad, Ateeque,Bawankule, Dnyaneshwar Umrao,Gupta, Amit Chand,Maurya, Anil Kumar,Nooreen, Zulfa,Saxena, Archana,Tandon, Sudeep
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p. 251 - 260
(2019/01/04)
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- Palladium-Catalyzed Oxidative Allylation of Sulfoxonium Ylides: Regioselective Synthesis of Conjugated Dienones
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The first examples of palladium-catalyzed allylic C-H oxidative allylation of sulfoxonium ylides to afford the corresponding conjugated dienones with moderate to good yields have been established. The features of this novel conversion include mild reaction conditions, wide substrate scope, and excellent regioselectivity.
- Li, Chunsheng,Li, Meng,Zhong, Wentao,Jin, Yangbin,Li, Jianxiao,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 872 - 875
(2019/05/16)
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- Synthesis method of 4-hydroxycinnamaldehyde compound
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The invention relates to the field of organic synthesis and agricultural chemistry, and particularly discloses a synthesis method of a 4-hydroxycinnamaldehyde compound shown as a formula II. The synthesis method comprises the following steps: with 4-hydroxy-allylbenzene as a raw material, firstly performing hydroxyl protection, then with 2, 3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an oxidant and water (H2O) as a nucleophile, oxidizing an allyl group into alpha, beta-unsaturated aldehyde (namely, a cinnamaldehyde structure) under a relatively mild condition, and finally performing deprotection to obtain a target product. The invention elaborates a novel synthesis method of the 4-hydroxycinnamaldehyde compound. The novel synthesis method has the characteristics of no transition metalparticipation, a simple and mild reaction condition, high product yield and the like, and has a wide application prospect in the field of the agricultural chemistry, especially in plant science and bioenergy conversion.
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Paragraph 0028; 0029; 0030
(2018/03/26)
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- DDQ-mediated oxidation of allylarenes: Expedient access to cinnamaldehyde-containing phenylpropanoids
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Phenylpropanoid natural products containing a cinnamaldehyde motif were easily synthesized from allylarenes mediated by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) oxidation. Representative examples described herein are five types of 4-hydroxycinnamaldehyde derivatives from monolignols biosynthesis, Boropinal C, and 7-methoxywutaifuranal from plant extracts. Especially, simple synthesis of 7-methoxywutaifuranal was exploited through selective mono-oxidation and subsequent isomerization-ring-closing-metathesis strategy.
- Jiang, Tao-Shan,Zhang, Qingqing,Li, Guohui,Cheng, Xi,Cai, Yongping
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p. 4611 - 4616
(2019/02/01)
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- Synthesis, antimicrobial activity and in silico studies on eugenol eters
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The results presented herein represent our continued study based on the modification of phenolic functionality in molecules originated from natural sources by acylation. A small focused library of nineteen eugenyl esters, with four of which are new compounds, is reported. All compounds were subjected to in vitro antimicrobial testing. In silico studies were carried out calculating physico-chemical, pharmacokinetic and toxicological properties, providing more data as additional guidance for further research.
- Lazarevi?, Jelena,Kolarevi?, Ana,Stojanovi?, Gordana,?melcerovi?, Andrija,Ciuffreda, Pierangela,Santaniello, Enzo
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p. 801 - 810
(2019/02/15)
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- Eugenol ester analogue and preparation method thereof as well as insecticide
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The invention relates to a eugenol ester analogue and application thereof and in particular relates to the eugenol ester analogue and a preparation method thereof as well as insecticide. The preparation method of the eugenol ester analogue comprises the following steps: (1) carrying out acylating chlorination on substituted carboxylic acid to obtain an intermediate product; (2) enabling the intermediate product and eugenol to react under the condition that an acid binding agent and an organic solvent exist, so as to obtain the eugenol ester analogue, wherein a substituent group in the substituted carboxylic acid is selected from one of C1 to C10 alkyl, C1 to C10 alkenyl, aryl, furyl and imidazolyl. The eugenol ester analogue prepared by the method provided by the invention has a remarkablelethal effect on agricultural insect pests and the insect pests also can have an octopamine agonist poisoning symptom; the eugenol ester analogue can be used as the insecticide and is widely appliedto agriculture.
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Paragraph 0053; 0056
(2018/07/30)
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- Eugenol derived immunomodulatory molecules against visceral leishmaniasis
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Visceral leishmaniasis (VL) is a life threatening infectious disease caused by Leishmania donovani. It leads to the severe immune suppression in the host defense system. Higher cytotoxicity, rigorous side effects and lower therapeutic indexes (TI) of current antileishmanial drugs have created a necessity to develop new molecules with better antileishmanial activity and high TI value. In this study, we have synthesized 36 derivatives of eugenol and screened them for their activity against promastigote and amastigote forms of L. donovani. Among the synthesized derivatives, comp.35 showed better antileishmanial activity against extra cellular promastigotes (IC50- 20.13 ± 0.91 μM) and intracellular amastigotes (EC50-4.25 ± 0.26 μM). The TI value (82.24 ± 3.77) was found to improve by 10–13 fold compared to Amphotericin B and Miltefosine respectively. Treatment with comp.35 (5 μg/ml) enhanced the nitric oxide (NO) generation, iNOS2 mRNA expression (～8 folds increase) and decreased the arginase-1 activity (～4 folds) in L. donovani infected peritoneal macrophages. Comp.35 had also increased the IL-12 (～6 folds) and decreased the IL-10 (～3 folds) mRNA expression and release in vitro. Results of in vivo studies revealed that comp.35 treatment at 25 mg/kg body weight efficiently cleared the hepatic and splenic parasite burden with enhanced Th1 response in L. donovani infected BALB/c mice. Hence, this study clearly represents comp.35, as an immunomodulatory molecule, can induce host protective immune response against visceral leishmaniasis through enhanced NO generation and Th1 response, which are essentials against this deadly disease.
- Charan Raja, Mamilla R.,Velappan, Anand Babu,Chellappan, Davidraj,Debnath, Joy,Kar Mahapatra, Santanu
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p. 503 - 518
(2017/08/22)
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- Anti-proliferative, apoptotic induction, and anti-migration effects of hemi-synthetic 1’S-1’-acetoxychavicol acetate analogs on MDA-MB-231 breast cancer cells
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Nine analogs of 1′S-1′-acetoxychavicol acetate (ACA) were hemi-synthesized and evaluated for their anticancer activities against seven human cancer cell lines. The aim of this study was to investigate the anti-proliferative, apoptotic, and anti-migration effects of these compounds and to explore the plausible underlying mechanisms of action. We found that ACA and all nine analogs were non toxic to human mammary epithelial cells (HMECs) used as normal control cells, and only ACA, 1′-acetoxyeugenol acetate (AEA), and 1′-acetoxy-3,5-dimethoxychavicol acetate (AMCA) inhibited the growth of MDA-MB-231 breast cancer cells with a half-maximal inhibitory concentration (IC50) value of 30.0 μM based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay results, and were selected for further investigation. DNA fragmentation assays showed that these three compounds markedly induced apoptosis of MDA-MB-231 cells. Western blot analysis revealed increased expression levels of cleaved PARP, p53, and Bax, while decreased expression levels of Bcl-2 and Bcl-xL were seen after treatment, indicating that apoptosis was induced via the mitochondrial pathway. Moreover, ACA, AEA, and AMCA effectively inhibited the migration of MDA-MB-231 cells. They also downregulated the expression levels of pFAK/FAK and pAkt/Akt via the integrin β1-mediated signaling pathway. Collectively, ACA and its hemi-synthetic analogs, AEA and AMCA are seen as potential anticancer agents following their abilities to suppress growth, induce apoptosis, and inhibit migration of breast cancer cells.
- Liew, Su Ki,Azmi, Mohamad Nurul,In, Lionel L. A.,Awang, Khalijah,Nagoor, Noor Hasima
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p. 2763 - 2776
(2017/10/11)
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- TiCl4/Et3N-Mediated Condensation of Acetate and Formate Esters: Direct Access to β-Alkoxy- and β-Aryloxyacrylates
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A methodology to build (E)-β-alkoxy- and (E)-β-aryloxyacrylate moieties from acetate and formate esters promoted by the TiCl4/Et3N system is presented. The reaction is compatible with a broad range of structural skeletons and elapses through an unusual condensation pathway. Taking into account the obtained results, we propose a plausible mechanism involving a bimetallic titanium intermediate for this type of transformation.
- álvarez-Calero, José María,Jorge, Zacarías D.,Massanet, Guillermo M.
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supporting information
p. 6344 - 6347
(2016/12/23)
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- Thymol and eugenol derivatives as potential antileishmanial agents
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In Northeastern Brazil visceral leishmaniasis is endemic with lethal cases among humans and dogs. Treatment is toxic and 5-10% of humans die despite treatment. The aim of this work was to survey natural active compounds to find new molecules with high activity and low toxicity against Leishmania infantum chagasi. The compounds thymol and eugenol were chosen to be starting compounds to synthesize acetyl and benzoyl derivatives and to test their antileishmanial activity in vitro and in vivo against L. i. chagasi. A screening assay using luciferase-expressing promastigotes was used to measure the growth inhibition of promastigotes, and an ELISA in situ was performed to evaluate the growth inhibition of amastigote. For the in vivo assay, thymol and eugenol derivatives were given IP to BALB/c mice at 100 mg/kg/day for 30 days. The thymol derivatives demonstrated the greater activity than the eugenol derivatives, and benzoyl-thymol was the best inhibitor (8.67 ± 0.28 μg/mL). All compounds demonstrated similar activity against amastigotes, and acetyl-thymol was more active than thymol and the positive control drug amphotericin B. Immunohistochemistry demonstrated the presence of Leishmania amastigote only in the spleen but not the liver of mice treated with acetyl-thymol. Thus, these synthesized derivatives demonstrated anti-leishmanial activity both in vitro and in vivo. These may constitute useful compounds to generate new agents for treatment of leishmaniasis.
- De Morais, Selene Maia,Vila-Nova, Nadja Soares,Bevilaqua, Claudia Maria Leal,Rondon, Fernanda Cristina,Lobo, Carlos Henrique,De Alencar Araripe Noronha Moura, Arlindo,Sales, Antnia Dbora,Rodrigues, Ana Paula Ribeiro,De Figuereido, Jos Ricardo,Campello, Claudio Cabral,Wilson, Mary E.,De Andrade, Heitor Franco
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p. 6250 - 6255
(2015/02/02)
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- An efficient method on nitration of eugenol using NH4NO3 and KHSO4
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The main objective of this research was to find new method for the synthesis of nitro-eugenol. Nitro-eugenol is of considerable importance in the production of other fine chemicals such as amino-eugenol for further chemical synthesis and has also been reported to possess antibacterial, antioxidant and anticancer properties. In an attempt to synthesize nitro-eugenol in high yield, some different nitration methods of eugenol have been applied. An efficient method using NH4NO3 in the presence of KHSO4 as a catalyst has been found to give nitro-eugenol in good yield.
- Sudarma,Wazni,Wildawaty,Yuanita,Suana
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p. 173 - 175
(2014/03/21)
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- A new ferrocene-based bulky pyridine as an efficient reusable homogeneous catalyst
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An effective approach to reusing a homogeneous catalyst has been demonstrated. A ferrocene-based bulky pyridine has been synthesized and utilized as a homogeneous catalyst for the synthesis of benzoylfumarates as well as for acetylation. After the reaction, the catalyst was separated by simple precipitation and reused without appreciable loss of activity. The Royal Society of Chemistry 2013.
- Kashyap, Bishwapran,Phukan, Prodeep
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p. 15327 - 15336
(2013/09/02)
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- Design and synthesis of novel pyrethriods containing eugenol moiety
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A novel series of pyrethriods was designed and synthesized by connecting various eugenol derivatives to either a chrysanthematic acid or 2-(4-chlorophenyl)-3-methylbutanoic acid. The insecticidal activity of target compounds has been evaluated by an immersion method on the fourth instar larvae of Culex pipens quinquefasciatus. The results revealed that the larvae were sensitive to synthesized compounds. Varying substituents in both acid moiety and eugenol group resulted in new compounds that exhibited different contact toxicity. Compound 3a showed the highest activity and is currently under further investigation.
- Wang, Xinlong,Yi, Meigui,Du, Quanhai,Wu, Aimin,Xiao, Rong
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p. 2827 - 2830,4
(2020/07/30)
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- Synthesis of novel isoxazolines via 1,3-dipolar cycloaddition and evaluation of anti-stress activity
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We have synthesized a series of novel isoxazolines via 1,3-dipolar cycloaddition of in situ generated nitrile oxide from 2,4-dimethoxy benzaldoxime and naphthaldehyde oxime with 4-allyl-2-methoxyphenol derivatives. The synthesized compounds were evaluated for anti-stress activity in acute stress (AS) induced peripheral changes. Adult male Sprague-Dawley rats, subjected to AS, cause a significant increase in gastric ulceration, adrenal gland weight, plasma glucose, corticosterone levels, and creatine kinase activity. Compounds 3d, 3g, 5b, 5c, 5d, and 5g displayed most promising anti-stress effect by reverting these peripheral stress parameters at a dose of 40 mg/kg p.o.
- Maurya, Rakesh,Ahmad, Ausaf,Gupta, Prasoon,Chand, Kailash,Kumar, Manmeet,Jayendra,Rawat, Preeti,Rasheed, Naila,Palit, Gautam
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body text
p. 139 - 145
(2012/03/10)
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- Larvicidal and structure-activity studies of natural phenylpropanoids and their semisynthetic derivatives against the tobacco armyworm Spodoptera litura (Fab.) (Lepidoptera: Noctuidae)
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The larvicidal activity of 18 phenylpropanoids, 1-18, including phenylpropenoate, phenylpropenal, phenylpropene, and their semisynthetic analogues, were evaluated against the tobacco armyworm, Spodoptera litura (FAB.), to identify promising structures with insecticidal activity. Amongst various phenylpropanoids, isosafrole, a phenylpropene, showed the best activity, with an LC50 value of 0.6 μg/leaf cm2, followed by its hydrogenated derivative dihydrosafrole (LC50=2.7 μg/leaf cm 2). The overall larvicidal activity of various phenylpropene derivatives was observed in the following order: isosafrole (6) >dihydrosafrole (16)>safrole (12)>anethole (4)>methyl eugenol (11)>eugenol (13)>β-asarone (8)>dihydroasarone (18)>dihydroanethole (15). Dihydrosafrole might be a promising compound, although presenting a lower larvicidal activity than isosafrole, because of its better stability and resistance to oxidative degradation (due to the removal of the extremely reactive olefinic bond) in comparison to isosafrole. Such structure-activity relationship studies promote the identification of lead structures from natural sources for the development of larvicidal products against S. litura and related insect pests.
- Bhardwaj, Anu,Tewary, Dhananjay Kumar,Kumar, Rakesh,Kumar, Vinod,Sinha, Arun Kumar,Shanker, Adarsh
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experimental part
p. 168 - 177
(2010/04/29)
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- Counterattack mode differential acetylative deprotection of phenylmethyl ethers: Applications to solid phase organic reactions
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A counterattack protocol for differential acetylative cleavage of phenylmethyl ether has been developed. The phenylmethyl moiety is liberated as benzyl bromide that is isolated and reused providing advantages in terms of waste minimization/utilization and atom economy. The applicability of this methodology has been extended for solid phase organic reactions with the feasibility of reuse of the solid support.
- Chakraborti, Asit K.,Chankeshwara, Sunay V.
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experimental part
p. 1367 - 1370
(2009/07/04)
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- A highly selective, high-speed, and hydrolysis-free O-acylation in subcritical water in the absence of a catalyst
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(Chemical Equation Presented) Fast and furious: A wide range of alcohols are acylated by acetic anhydride, in the absence of catalyst, in subcritical water in a flow-type microreaction system. The esters are selectively produced in high yields at temperatures of 200 to 250°C. Varying the amount of acetic anhydride added with respect to the alcohols allows the regioselective acylation of one or both hydroxy groups of various dihydroxy compounds (see picture).
- Sato, Masahiro,Matsushima, Keiichiro,Kawanami, Hajime,Ikuhsima, Yutaka
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p. 6284 - 6288
(2008/04/05)
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- Indium(III) chloride as a new, highly efficient, and versatile catalyst for acylation of phenols, thiols, alcohols, and amines
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Indium(III) chloride efficiently catalyses the acylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions. Acid sensitive alcohols are smoothly acylated without competitive side reactions. Acylation of 2-hydroxynaphthalene is carried out with carboxylic acids adopting the mixed anhydride protocol using trifluoroacetic anhydride.
- Chakraborti, Asit K.,Gulhane, Rajesh
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p. 6749 - 6753
(2007/10/03)
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- Retention behavior of compounds with active hydrogen atoms and their acetylated derivatives in reversed-phase HPLC
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In view of poor interlaboratory reproducibility of retention indices I in reversed-phase high-performance liquid chromatography, not the indices themselves but their differences for reactants and products of interaction with various reagents can be used to identify compounds with active hydrogen atoms. For acetylated derivatives of phenols and aromatic amines, the quantity ?I = I(ArXH) -I(ArXCOCH3), where X = O or NH. has statistically significant distinguishable values of 126 ± 15 and 70 ± 20, respectively. The additivity of the parameters ?I is first revealed for the polyfunctional compounds of these classes that are incapable of intramolecular hydrogen bonding. Abnormal ?I values and deviations from the additivity rule are observed only for substances with intramolecular hydrogen bonding. This finding can be used to confirm the presence of relevant structural units in molecules.
- Zenkevich,Kosman
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p. 1173 - 1176
(2007/10/03)
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