- Probing the effects of microwave irradiation on enzyme-catalysed organic transformations: The case of lipase-catalysed transesterification reactions
-
The lipase-catalysed transesterification reaction of methyl acetoacetate in toluene as a solvent has been studied using carefully controlled conditions. Results suggest that microwave heating does not have a noticeable effect on reaction rate or product conversion. This journal is The Royal Society of Chemistry.
- Leadbeater, Nicholas E.,Stencel, Lauren M.,Wood, Eric C.
-
-
Read Online
- Synthesis, study of 3D structures, and pharmacological activities of lipophilic nitroimidazolyl-1,4-dihydropyridines as calcium channel antagonist
-
QSAR studies indicated that the potency of nifedipine analogues was dependent upon lipophilicity, an electronic term and separated terms for each position on the DHP ring. Changes in the substitution pattern at the C3, C4, and C5 positions of DHPs alter potency, tissue selectivity, and the conformation of the 1,4-DHP ring. In this project a group of alkyl ester analogues of new derivatives of nifedipine, in which the ortho-nitrophenyl group at position 4 is replaced by a 1-methyl-5-nitro-2-imidazolyl substituent, and the methyl group at position 6 is replaced by a phenyl substituent, were synthesized and evaluated as calcium channel antagonist using the high K+ contraction of guinea-pig ileal longitudinal smooth muscle. The results for asymmetrical esters showed that lengthening of the substituent in C3 ester substituent increased activity. When increasing of the length is accompanied by increasing the hindrance, the activity decreased. The results demonstrate that all compounds were more active or similar in effect to that of the reference drug nifedipine.
- Miri, Ramin,Javidnia, Katayoun,Sarkarzadeh, Hasti,Hemmateenejad, Bahram
-
-
Read Online
- Synthesis and evaluation of pharmacological activities of 3,5-dialkyl 1,4-dihydro-2,6-dimethyl-4-nitroimidazole-3,5-pyridine dicarboxylates
-
New analogues of nifedipine, in which the 2-nitrophenyl group at position 4 is replaced by a 1 -methyl-5-nitro-2-imidazolyl substituent, were synthesized. The symmetrical dialkyl 1,4-dihydro-2,6-dimethyl-4-(1-methyl-5-nitro-2-imidazolyl)-3, 5-pyridinedicarboxylates were prepared by a classical Hantzsch condensation. The asymmetrical analogues were synthesized using a procedure reported by Iwanami that involved the condensation of alkylacetoacetate with methyl-, ethyl- or isopropyl-3-aminocrotonate and 1 -methyl-5-nitroimidazole-2-carboxaldehyde. Calcium channel antagonist activities were determined in vitro using a guinea pig ileum longitudinal smooth muscle (GPILSM) assay. Many compounds exhibited superior, or equipotent, calcium antagonist activity (IC50 = 10- 10 to 10-13 M range) relative to the reference drug nifedipine (IC50 = 1.09? 0.12 × 10-11 M). Antinociceptive effects of some compounds were evaluated by the mouse tail-flick assay in vivo. Results demonstrate that some of the compounds were active as an antinociceptive.
- Miri, Ramin,Javidnia,Kebriaie-Zadeh,Niknahad,Shaygani,Semnanian,Shafiee
-
-
Read Online
- Br?nsted acidic cellulose-PO3H: An efficient catalyst for the chemoselective synthesis of fructones and trans-esterification via condensation of acetoacetic esters with alcohols and diols
-
Cellulose is the most abundant organic source and has expedient a great deal of interest as renewable and emerged as sustainable feedstock. The functionalization of cellulose as designed catalytic system intriguing furnished to the production of fine chemicals. Herein, we synthesized an environmental friendly solid acid catalyst by functionalizing cellulose with phosphoric acid (PO3H). The successful functionalization of cellulose with PO3H was confirmed by 31P NMR, ICP-OES, FE-SEM, and XPS analysis. ICP-OES revealed the presence of phosphorus content of ~1.0 wt. % on the catalyst's surface while elemental mapping by FESEM and XPS shows a uniform distribution of phosphorus over the material. The synthesized solid acid catalyst was utilized for condensation of diols with acetoacetic esters in solvent-free conditions to synthesize fine chemicals. The present approach not only circumvented the one-step protection and other products but more fascinatingly provided trans-esterification of acetoacetic esters with diols and n-alcohols. The catalyst was successfully used for chemoselective protection on ethyl acetoacetate with 1, 2 diols to essential fructone molecule with ~100% conversion and 99% selectivity. The results suggested that the catalyst has the advantage over commercial solid acid heterogeneous and homogeneous catalysts.
- Naikwadi, Dhanaji R.,Singh, Amravati S.,Biradar, Ankush V.
-
-
- N, N’-dimethyl formamide (DMF) mediated Vilsmeier–Haack adducts with 1,3,5-triazine compounds as efficient catalysts for the transesterification of β-ketoesters
-
N, N’-dimethyl formamide (DMF) mediated Vilsmeier–Haack (VH) adducts with 1,3,5-triazine compunds such as trichloroisocyanuric acid (TCCA) and trichlorotriazine (TCTA) were prepared by replacing classical oxy chlorides POCl3, and SOCl2, which were explored as efficient catalysts for the transesterification of β-ketoesters. The prepared (TCCA/DMF) and (TCTA/DMF) adducts improved greenery of the classical Vilsmeier–Haack reagents (POCl3/DMF), and (SOCl2/DMF), and demonstrated their better efficient catalytic ativity. Reaction times were in the range: 3.5 to 6.5 hr (SOCl2/DMF); 2.8–5.2 hr (POCl3/DMF); 2.5–5.2 hr (TCCA/DMF) and 2.5–5.0 hr (TCTA/DMF) catalytic systems. Ultrasonically (US) assisted protocols with these reagents further reduced the reaction times (two to three times), while microwave assisted (MW) protocols with these reagents were much more effective. The reactions could be completed in only few seconds (less than a minute) in MWassisted protocols as compared to US assited reactions, followed by good product yields.
- Chityala, Yadaiah,Duguta, Govardhan,Kamatala, Chinna Rajanna,Muddam, Bhooshan,Mukka, Satish Kumar
-
supporting information
p. 1641 - 1655
(2020/05/25)
-
- COMPOSITIONS COMPRISING A POLYMERIC NETWORK
-
The present invention relates to a composition comprising a polymeric network having at least one unit of formula (I), (II), and/or (III); (I) (II) (III) wherein said composition is obtained by contacting at least one compound A comprising at least two functions selected from the group of function of formula X—C(═O)—CHR1—C(═O)—R2, —C(═O)—C—R2; or —C(═O)—CR1═CR2—NR4R5; wherein at least 25% by weight of compounds A have a functionality ≦5, with % by weight relative to the total weight of compounds A; with at least one compound B comprising at least one NH2, or NH3+ groups; wherein X, R1, R2, R3, R4, R5, L1 and L2 have the same meaning as that defined in the claims. The present invention also relates to a compound comprising at least two units and at most 5 units of formula (I), (II), and/or (III); wherein R1, R2, R3, X, L1 and L2 have the same meaning as that defined in the claims. The present invention also relates to processes for preparing said composition and said compounds, to material, articles, and polymers comprising or using said compositions and compounds, and the use thereof.
- -
-
Paragraph 0528
(2017/12/15)
-
- Ag-Cu nanoparticles as efficient catalysts for transesterification of β-keto esters under acid/base-free conditions
-
Transesterification of β-keto esters and alcohols are traditionally catalyzed by acid or basic catalysts. However, these traditional catalysts do not always meet the requirements of modern synthetic chemistry which need to be highly efficient, selective, and environmentally friendly. In this work, Ag-Cu metal sites were first introduced as transesterification catalysts. The effect of the support, Ag:Cu molar ratio, and reaction conditions were investigated. The Ag-Cu metal sites were proved to be active in the β-ketoester transesterification with various alcohols, having yields comparable to the conventional acid- or base-catalysts.
- Yue, Hongmei,Yu, Hao,Liu, Sheng,Xu, Chunli
-
p. 19041 - 19051
(2016/03/01)
-
- Copper-catalyzed radical coupling of 1,3-dicarbonyl compounds with terminal alkenes for the synthesis of tetracarbonyl compounds
-
A novel and efficient copper-catalyzed radical cross-coupling of 1,3-dicarbonyl compounds with terminal alkenes for the synthesis of tetracarbonyl compounds with a quaternary carbon atom has been developed. Mechanistically, this transformation involves the construction of two C-C bonds and two CO bonds in a one-pot process. The reaction tolerates a wide range of functional groups and proceeds under mild conditions.
- Zhang, Mei-Na,Zhao, Mi-Na,Chen, Ming,Ren, Zhi-Hui,Wang, Yao-Yu,Guan, Zheng-Hui
-
supporting information
p. 6127 - 6130
(2016/05/19)
-
- Vinylogous urethane vitrimers
-
Vitrimers are a new class of polymeric materials with very attractive properties, since they can be reworked to any shape while being at the same time permanently cross-linked. As an alternative to the use of transesterification chemistry, we explore catalyst-free transamination of vinylogous urethanes as an exchange reaction for vitrimers. First, a kinetic study on model compounds reveals the occurrence of transamination of vinylogous urethanes in a good temperature window without side reactions. Next, poly(vinylogous urethane) networks with a storage modulus of ≈2.4 GPa and a glass transition temperature above 80 °C are prepared by bulk polymerization of cyclohexane dimethanol bisacetoacetate, m-xylylene diamine, and tris(2-aminoethyl)amine. The vitrimer nature of these networks is examined by solubility, stress-relaxation, and creep experiments. Relaxation times as short as 85 s at 170 °C are observed without making use of any catalyst. In addition, the networks are recyclable up to four times by consecutive grinding/compression molding cycles without significant mechanical or chemical degradation. Catalyst-free vitrimers based on the transamination of vinylogous urethanes are prepared from readily accessible chemicals. These high Tg, cross-linked materials exhibit excellent mechanical properties, while the exchangeable bonds enable full stress-relaxation on short time scales and recycling over many cycles.
- Denissen, Wim,Winne, Johan M.,Du Prez, Filip E.,Rivero, Guadalupe,Nicola, Renaud,Leibler, Ludwik
-
p. 2451 - 2457
(2015/09/08)
-
- Prussian blue as an efficient catalyst for rate accelerations in the transesterification of β-ketoesters
-
Prussian blue triggered transesterification of ethylacetoacetate with various alcohols underwent efficiently. The reaction is mild, eco-friendly, and selective with good yields. The proposed reaction pathway depicts the formation of an intermediate by the interaction of β-ketoesters with catalytic site of the Prussian blue, followed by nucleophilic attack of the alcohol at the electrophilic center followed by successive elimination of the proton to give the product. Observed longer reaction times under conventional conditions reduced amazingly under sonication and microwave irradiation followed enhanced yield of products.
- Srinivas,Rajanna,Krishnaiah,Kumar, M. Satish,Reddy, J. Narender
-
p. 1212 - 1220
(2014/04/17)
-
- Manganese(II) salts as efficient catalysts for chemo selective transesterification of β-keto esters under non-conventional conditions
-
Transesterification of β-ketoesters with various alcohols has been studied under conventional and non-conventional conditions using desktop chemicals such as Mn(II) salts as catalysts. These methods offered transesterification of β-ketoesters in good yields with dramatic rate accelerations and reduced reaction times. The developed protocols under nonconventional methods such as sonication and microwave irradiation are highly promising compared with the existing procedures.
- Krishnaiah,Sandeep,Kondhare,Rajanna,Narendar Reddy,Rajeshwar Rao,Zhubaidha
-
p. 703 - 706
(2013/02/23)
-
- Design and synthesis of new 1,4-dihydropyridines containing 4(5)-chloro-5(4)-imidazolyl substituent as a novel calcium channel blocker
-
New analogues of nifedipine, in which the ortho-nitro phenyl group at position 4 has been replaced by 4(5)-chloro-5(4)-imidazolyl substituent and which are able to interact with the receptor by hydrogen binding were designed, synthesized, and evaluated as calcium channel antagonists. The designed dihydropyridines were synthesized using the Hantzsch condensation and evaluated as calcium channel antagonists using the high K+ contraction of guineapig ileal longitudinal smooth muscle. A docking study was performed using the AutoDock4 program, and QSAR equations were obtained using multilinear regression. Our computational studies indicated that the oxygen of the ester (O10) and the N3′ of the imidazole ring form a hydrogen bonding interaction with the NH of HIS 363 and NH of LYS354, respectively, and that the sum of the BEHp5 and RDF075p are the most significant descriptors. The results of calcium channel antagonist evaluation demonstrated that increasing the chain length in C3 and C5 ester substituents increased activity. The most potent compound was the bis-phenylpropyl ester (5l) derivative, in that it was more active than the reference drug nifedipine and that the bis-phenylethyl ester (5k) derivative had comparable activity with nifedipine. The present research revealed that the 4(5)-chloro-5(4)-imidazolyl moiety is a bioisoster of o-nitrophenyl in nifedipine and provided novel dihydropyridines with more activity as calcium channel antagonists.
- Iman, Maryam,Davood, Asghar,Nematollahi, Ali Reza,Dehpoor, Ahmad Rerza,Shafiee, Abbas
-
experimental part
p. 1417 - 1426
(2012/05/04)
-
- Molecular iodine in ionic liquid: A green catalytic system for esterification and transesterification
-
Esterification of carboxylic acids and transesterification of-ketoesters with alcohols have been developed using a catalytic amount of iodine in polyethylene glycol (PEG) ionic liquid (IL 1000) to afford the corresponding esters in good yields. By simple separation of the ionic-liquid phase containing the iodine, the system of I2/IL 1000 can be reused several times. Copyright
- Ren, Yiming,Cai, Chun
-
scheme or table
p. 1670 - 1676
(2010/08/03)
-
- BF3OEt2: An efficient catalyst for transesterification of β-ketoesters
-
A facile and selective transesterification of β-ketoesters using BF3OEt2 as catalyst is described. The emphasis has been placed on the reaction of methyl acetoacetate with a series of alcohols of different structures, leading in all cases to good to excellent yields.
- Yang, Jinhui,Ji, Congbin,Zhao, Yanmin,Li, Yunfeng,Jiang, Shizhi,Zhang, Zhiwei,Ji, Yongqiang,Liu, Wanyi
-
experimental part
p. 957 - 963
(2010/06/12)
-
- Synthesis and biological evaluation of some new 1,4-dihydropyridines containing different ester substitute and diethyl carbamoyl group as anti-tubercular agents
-
Tuberculosis is a leading infectious cause of death worldwide. Because of the concern of the resistance to most of the commonly used drugs displayed by the considered mycobacteria, most efforts have been done to introduce new anti-tubercular agents. Recent studies showed that 1,4-dihydropyridine-3,5-dicarbamoyl derivatives with lipophilic groups have significant anti-tubercular activity. In this study, we synthesized new derivatives of 1,4-dihydropyridines in which different alkyl and aryl esters and diethyl carbamoyl are substituted in C-3 and C-5 of the DHP ring. In addition nitroimidazole ring is substitutes at C-4 position. These asymmetric analogues were synthesized by a modified Hantzsh reaction using procedure reported by Meyer. The in vitro anti-tubercular activity of compounds against Mycobacterium tuberculosis was evaluated. The results indicate that the compounds containing aromatic esters are more potent than alkyl ones. The most potent aromatic compound (R = 3-phenylpropyl) exhibits comparable anti-tubercular activity (MIC = 1 μmol/ml) with reference compound isoniazide (INH) (MIC = 1 μmol/ml). Conformational analysis, SAR studies of these compounds showed that increasing in lipophilicity and rotable bonds of these compounds resulted in increasing anti-tubercular activity.
- Khoshneviszadeh, Mehdi,Edraki, Najmeh,Javidnia, Katayoun,Alborzi, Abdolvahab,Pourabbas, Bahman,Mardaneh, Jalal,Miri, Ramin
-
experimental part
p. 1579 - 1586
(2009/07/11)
-
- Lipophilic 4-imidazoly-1,4-dihydropyridines: Synthesis, calcium channel antagonist activity and protection against pentylenetetrazole-induced seizure
-
A group of alkyl, cycloalkyl and aryl ester analogs of nifedipine, in which the o-nitrophenyl group at position 4 is replaced by a 2-phenyl-4(5)-imidazolyl substituent, were synthesized and evaluated as calcium channel antagonist using the high K+ contraction of guinea-pig ileal longitudinal smooth muscle, and the activity of 5a-d, 8b and 8f against pentylenetetrazole (PTZ)-induced seizure was assessed. The results for symmetrical esters showed that lengthening of the methylene chain in C3 and C5 ester substituents increased activity. When increasing of the length is accompanied by increasing the hindrance, the activity decreased. In contrast to symmetrical derivatives, comparison of the activities of asymmetrical esters showed that increasing the length of the methylene chain was accompanied by a decrease in their activity. The results demonstrate that 8a was more active, and 5c and 8f were similar in effect to that of the reference drug nifedipine. The time-course of anticonvulsant effect on PTZ-induced seizure threshold of said compounds was assessed and showed that increasing the lipophilicity decreases the time needed for maximum effect. Mice treated with intraperitoneal injection of 25 mg/kg of these derivatives all exhibited increase seizure threshold as compared with control.
- Navidpour, Latifeh,Shafaroodi, Hamed,Miri, Ramin,Dehpour, Ahmad Reza,Shafiee, Abbas
-
p. 261 - 269
(2007/10/03)
-
- A Simple and Efficient Method for Transesterification of β-Ketoesters Catalysed by Iodine
-
A facile transesterification of β-ketoesters using catalytic iodine is described.
- Chavan, Subhash P.,Kale, Ramesh R.,Shivasankar,Chandake, Sanjay I.,Benjamin, Swapnanjali B.
-
p. 2695 - 2698
(2007/10/03)
-
- Method for preparing chiral diphosphines
-
The invention concerns a method for preparing a compound of formula (1) wherein: A represents naphthyl or phenyl optionally substituted; and Ar1, Ar2independently represent a saturated or aromatic carbocyclic group, optionally substituted.
- -
-
-
- A3 adenosine receptor antagonists
-
Disclosed are pyridine and dihydropyridine derivatives, pharmaceutical compositions comprising one or more of these derivatives, and a method of selectively blocking an A3adenosine receptor of a mammal by the use of one or more of these derivatives. An example of the pyridine derivative is of the formula (I): wherein R2is ethyl, R3is ethylsulfanyl; R4is ethyl, propyl, or hydroxypropyl; R5is ethyl, propyl, fluoroethyl, or fluoropropyl; and R6is phenyl or fluorophenyl. The derivatives of the present invention can be used for inhibiting binding of ligands to an adenosine receptor. The derivatives also can be used for characterizing an adenosine receptor.
- -
-
-
- Lithium perchlorate as an efficient catalyst for selective transesterification of β-Keto esters essentially under neutral conditions
-
Lithium perchlorate catalysed efficient transesterification of β-keto esters has been carried out, which affords various esters under almost neutral conditions.
- Bandgar,Sadavarte,Uppalla
-
p. 1338 - 1340
(2007/10/03)
-
- Chemoselective transesterification of β-keto esters under neutral conditions using NBS as a catalyst
-
Facile and selective transesterification of β-keto esters using N-bromosuccinimide (NBS) as an efficient and neutral catalyst is described.
- Bandgar,Uppalla,Sadavarte
-
p. 1715 - 1718
(2007/10/03)
-
- Sodium perborate catalyzed selective transesterification of β-keto esters under neutral conditions
-
Transesterification of β-keto esters with various alcohols has been carried out using sodium perborate as an inexpensive catalyst under neutral conditions. The effectiveness of the protocol is manifested in its selectivity towards β-keto esters whereas other esters are found to be unreactive under these reaction conditions.
- Bandgar,Sadavarte,Uppalla
-
p. 894 - 895
(2007/10/03)
-
- Asymmetric hydrogenation method of a ketonic compound and derivative
-
The present invention relates to a process for the asymmetric hydrogenation of a ketonic compound and derivative. The invention relates to the use of optically active metal complexes as catalysts for the asymmetric hydrogenation of a ketonic compound and derivative. The process for the asymmetric hydrogenation of a ketonic compound and derivative is characterized in that the asymmetric hydrogenation of said compound is carried out in the presence of an effective amount of a metal complex comprising as ligand an optically active diphosphine corresponding to one of the following formulae: STR1
- -
-
-
- Structure-activity relationships and molecular modeling of 3,5-diacyl- 2,4-dialkylpyridine derivatives as selective A3 adenosine receptor antagonists
-
The structure-activity relationships of 6-phenyl-1,4-dihydropyridine derivatives as selective antagonists at human A3 adenosine receptors have been explored (Jiang et al. J. Med. Chem. 1997, 39, 4667-4675). In the present study, related pyridine derivatives have been synthesized and tested for affinity at adenosine receptors in radioligand binding assays. K(i) values in the nanomolar range were observed for certain 3,5-diacyl-2,4- dialkyl-6-phenylpyridine derivatives in displacement of [125I]AB-MECA (N6-(4-amino-3-iodobenzyl)-5'-N-methylcarbamoyladenosine) at recombinant human A3 adenosine receptors. Selectivity for A3 adenosine receptors was determined vs radioligand binding at rat brain A1 and A(2A) receptors. Structure-activity relationships at various positions of the pyridine ring (the 3- and 5-acyl substituents and the 2- and 4-alkyl substituents) were probed. A 4-phenylethynyl group did not enhance A3 selectivity of pyridine derivatives, as it did for the 4-substituted dihydropyridines. At the 2-and 4-positions ethyl was favored over methyl. Also, unlike the dihydropyridines, a thioester group at the 3-position was favored over an ester for affinity at A3 adenosine receptors, and a 5-position benzyl ester decreased affinity. Small cycloalkyl groups at the 6-position of 4-phenylethynyl-1,4- dihydropyridines were favorable for high affinity at human A3 adenosine receptors, while in the pyridine series a 6-cyclopentyl group decreased affinity. 5-Ethyl 2,4-diethyl-3-(ethylsulfanylcarbonyl)-6-phenylpyridine-5- carboxylate, 38, was highly potent at human A3 receptors, with a K(i) value of 20 nM. A 4-propyl derivative, 39b, was selective and highly potent at both human and rat A3 receptors, with K(i) values of 18.9 and 113 nM, respectively. A 6-(3-chlorophenyl) derivative, 44, displayed a K(i) value of 7.94 nM at human A3 receptors and selectivity of 5200-fold. Molecular modeling, based on the steric and electrostatic alignment (SEAL) method, defined common pharmacophore elements for pyridine and dihydropyridine structures, e.g., the two ester groups and the 6-phenyl group. Moreover, a relationship between affinity and hydrophobicity was found for the pyridines.
- Li, An-Hu,Moro, Stefano,Melman, Neli,Ji, Xiao-Duo,Jacobson, Kenneth A.
-
p. 3186 - 3201
(2007/10/03)
-
- Synthesis and calcium-channel antagonist activity of 4-imidazolyl-1,4-dihydropyridines
-
The o-nitrophenyl group at position 4 of dihydropyridine of nifedipine analogues was replaced by 1-methylimidazole. These compounds were evaluated as calcium-channel antagonists using the high K+ contraction of guinea-pig ileal longitudinal smooth muscle. The results for the symmetrical esters showed that increasing the length of methylene chain of ester more than 3 units decreases activity. For cyclic esters, cyclopropylmethyl ester was more active than cyclohexylmethyl ester. Our results revealed two compounds with activities similar to the reference drug nifedipine; the symmetrical cyclopropylmethyl ester, and the asymmetrical phenethyl ethyl derivatives were the most potent antagonists tested.
- Pourmorad,Hadizadeh,Shafiee
-
p. 165 - 168
(2007/10/03)
-
- Chemoselectivity in the Reactions of Acetylketene and Acetimidoylketene: Confirmation of Theoretical Predictions
-
Acetylketene (1) was generated by flash pyrolysis of 2,2,6-trimethyl-4H-1,3-dioxin-4-one (6). The selectivities of 1 toward a number of representative functional groups were measured for the first time in a series of competitive trapping reactions. The trend in reactivities toward 1 follows the general order amines > alcohols aldehydes ≈ ketones and can be rationalized by considering both the nucleophilicity and the electrophilicity of the reacting species. Alcohols show significant selectivity based on steric hindrance, with MeOH ≈ 1° > 2° > 3°. These selectivities are consistent with the activation energies and the pseudopericyclic transition structure previously calculated for the addition of water to formylketene. The results, presented here, of ab initio transition structure calculations for the addition of ammonia to formylketene are qualitatively consistent with the experimental trends as well. N-Propylacetacetimidoylketene (2) was generated by the solution pyrolysis of tert-butyl N-propyl-3-amino-2-butenoate (9a) and showed similar selectivity toward alcohols as opposed to ketones and similar steric discrimination toward alcohols. This is again in agreement with previous ab initio calculations. Taken together, these experimental trends in the reactivities of both 1 and 2 toward a variety of reagents provide strong, although indirect support for the planar, pseudopericyclic transition structures for these reactions which are predicted by ab initio calculations.
- Birney, David M.,Xu, Xiaolian,Ham, Sihyun,Huang, Xiaomeng
-
p. 7114 - 7120
(2007/10/03)
-
- Cyclicondensation of alkylacetoacetates with 1,3,5-trinitrobenzene and base
-
The condensation reaction between alkylacetoacetates and 1,3,5-trinitrobenzene has been carried out in the presence of triethylamine and diethylamine as the catalysing bases.The reaction kinetics with different alkylacetoacetates is studied and linear steric energy correlation is established.The resultant condensation product has been characterized by elemental analysis, IR, UV/visible and 1H NMR spectral studies.
- Radha, N.,Kamala, V.
-
p. 399 - 403
(2007/10/03)
-
- Substituted biphenyls
-
Substituted biphenyls can be prepared by reduction of appropriate ketones and, if appropriate, subsequent hydrolysis, cyclization, hydrogenation and separation of isomers. The substituted biphenyls can be used as active compounds in medicaments.
- -
-
-
- Oxygen Nucleophile Induced Ring Cleavage of 6-Methyl-1,3-oxazine-2,4(3H)-dione -- A Case of Nucleophilic Attack at C-4
-
Alcohols in the presence of triethylamine react with 6-methyl-1,3-oxazine-2,4(3H)-dione (2), preferentially at C-4 instead of C-2 to afford the corresponding alkyl acetoacetates (4), and alkyl carbamates (5).
- Singh, Harjit,Kumar, Subodh
-
-
- 1,4-Dihydropyridine carboxylic acid esters useful as coronary vessel dilators and anti-hypertensives
-
Certain 1,4-dihydropyridine carboxylic acid esters or their pharmaceutically acceptable non toxic salts are useful as coronary vessel dilators and antihypertensives.
- -
-
-