- Chemoselectivity in the Reactions of Acetylketene and Acetimidoylketene: Confirmation of Theoretical Predictions
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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
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Read Online
- PORPHYRINS. 18. SYNTHESIS OF OCTAPROPYLPORPHYRIN BY THE METHOD OF MONOPYRROLE CYCLOTETRAMERIZATION OF 5-CARBOXY-2-METHOXYMETHYL-3,4-DIPROPYLPYRROLE. INVESTIGATION OF THE THERMOLYSIS OF meso-N-METHYLFORMALDIMINEOCTAPROPYLPORPHYRIN
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The synthesis of octapropylporphyrin on the basis of 5-carboxy-2-methoxymethyl-3,4-dipropylpyrrole was realized.It was demonstrated that in the thermolysis of meso-N-methylformaldimineoctapropylporphyrin, 31,51-cyclo-31-ethylidene- and 31,51-cyclo-31-ethyl-51-(N-methylimine) derivatives are also formed in addition to 31,51-cyclo-31-ethylheptapropylporphyrin.
- Shul'ga, A. M.,Ponomarev, G. V.
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Read Online
- Csp3-H monofluoroalkenylation via stereoselective C-F bond cleavage
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A practical nickel- and photoredox-catalyzed Csp3-H monofluoroalkenylation through chelation-assisted Csp2-F bond cleavage of gem-difluoroalkenes for the synthesis of stereodefined tetrasubstituted fluoroalkenes has been developed. Moreover, the gem-difluoroalkenes can also undergo photoredox-catalyzed cascade twofold C-F diaminomethylation. This journal is
- Hu, Binjing,Hu, Ying,Li, Jie,Liu, Xingchen,Ren, Zhouyang
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supporting information
p. 2734 - 2737
(2022/03/02)
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- Revisiting ageless antiques; synthesis, biological evaluation, docking simulation and mechanistic insights of 1,4-Dihydropyridines as anticancer agents
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The historic DHP nucleus was serendipitously discovered by Arthur Hantzsch about 130 years ago and is still considered a hidden treasure for various pharmacological activities. Twenty-one DHP analogues were synthesized using the expedient one pot Hantzsch synthesis for screening as anticancer agents. Initially, the in vitro anti-proliferative single dose against a panel of 18 cancer cell lines showed that compounds 11b and 8f were the superlative candidates regarding their antitumor effect (GI% mean = 66.40% and 50.42%, correspondingly) compared to cisplatin (GI% mean = 65.58%) and doxorubicin (GI% mean = 74.56%). Remarkably, compound 11b showed a remarkable MDA-MB-468 anticancer activity (GI%=80.81%), higher than cisplatin (64.44%) and doxorubicin (76.72%), as well as strong antitumor activity against lung cancer A549 (GI%= 83.02%), more powerful than both cisplatin and doxorubicin. Compound 11b exhibited an exceptional anticancer activity against lung cancer cell line (A549) as its GI50 in nanomolar was (540 nM) with a 9-fold increase greater than cisplatin (GI50 = 4.93 μM) and with a selectivity index = 131 to cancer cells over normal cells. Further mechanistic investigations proved that DHPs anticipate simultaneously TOPI and RTKs (VEGFR-2, HER-2 and BTK) which can stimulate BAX/BAK and the executioner caspases via rtPCR studies.
- Sidhom, Peter A.,El-Bastawissy, Eman,Salama, Abeer A.,El-Moselhy, Tarek F.
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supporting information
(2021/06/21)
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- Visible-light-driven radical 1,3-addition of selenosulfonates to vinyldiazo compounds
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Herein, we report a visible-light-driven radical 1,3-selenosulfonylation of vinyldiazo compounds with selenosulfonates, providing various γ-seleno allylic sulfones in good yields. This photochemical reaction was carried out at room temperature in an open flask using ethyl acetate as the solvent without any photocatalysts or additives. The control experiments corroborated that the 1,3-addition proceeded via a radical-chain propagation process. The synthetic applications of the resulting products were demonstrated by deselenization, reduction, bromination and allylation.
- Li, Weiyu,Zhou, Lei
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supporting information
p. 6652 - 6658
(2021/09/10)
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- N, N’-dimethyl formamide (DMF) mediated Vilsmeier–Haack adducts with 1,3,5-triazine compounds as efficient catalysts for the transesterification of β-ketoesters
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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
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supporting information
p. 1641 - 1655
(2020/05/25)
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- Design, synthesis, and molecular docking study of new monastrol analogues as kinesin spindle protein inhibitors
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Lung, colorectal, and breast cancers are the top three types of cancer by incidence and are responsible for one-third of the cancer incidence and mortality. A series of 18 3,4-dihydropyrimidine analogues bearing a 1,2-methylenedioxybenzene component at position 4 with diverse side chains at positions 5 and 6 was designed and synthesized as inhibitors of the Eg5 kinesin enzyme. Target compounds were screened for their anticancer activity according to the NCI-USA protocol toward a panel of 60 cancer cell lines. Compounds 12a and 12b displayed the best antiproliferation activity against many cell lines. Interestingly, compound 12a displayed lethal effects against non-small-cell lung cancer NCI-H522 cells (?42.26%) and MDA-MB-468 breast cancer cells (?1.10%) at a single-dose assay concentration of 10?5 M. Compounds 11c, 11d, 11g, 12a–d, 13, 15, and 18a were assayed against the kinesin enzyme, with IC50 values ranging from 1.2 to 18.71 μM, which were more potent compared with monastrol (IC50 = 20 μM). Cell cycle analysis of NCI-H522 cells treated with compound 12a showed cell cycle arrest at the G2/M phase. Furthermore, the expression levels of active caspase-3 and -9 were measured. A molecular docking study was performed for some demonstrative compounds as well as monastrol docked into the allosteric binding site of the kinesin spindle protein.
- El-Hamamsy, Mervat H.,Sharafeldin, Nabaweya A.,El-Moselhy, Tarek F.,Tawfik, Haytham O.
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- General [4 + 1] Cyclization Approach to Access 2,2-Disubstituted Tetrahydrofurans Enabled by Electrophilic Bifunctional Peroxides
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A general [4 + 1] cyclization reaction of carbonyl nucleophiles with 2-iodomethylallyl peroxides, which function as unique electrophilic oxygen synthons, for the synthesis of a broad range of 2,2-disubstituted tetrahydrofurans is achieved under operationally simple conditions. The unprecedented asymmetric version of such reaction is also realized via chiral auxiliary-assisted cyclization, thus providing a distinct approach to access chiral tetrahydrofurans with high diastereoselectivities. The new method can be applied to the synthesis of core structure of posaconazole drug.
- Gao, Min,Zhao, Yukun,Zhong, Chen,Liu, Shengshu,Liu, Pengkang,Yin, Qi,Hu, Lin
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supporting information
p. 5679 - 5684
(2019/08/01)
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- Synthesis method of tert-butyl acetoacetate
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The invention discloses a synthesis method of tert-butyl acetoacetate. The method comprises the following steps that tertiary butanol and catalysts are added into a reaction container; the catalysts are selected from aliphatic amine catalysts or tertiary
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Paragraph 0039-0050
(2018/05/16)
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- Hypochlorite-Mediated Modulation of Photoinduced Electron Transfer in a Phenothiazine–Boron dipyrromethene Electron Donor–Acceptor Dyad: A Highly Water Soluble “Turn-On” Fluorescent Probe for Hypochlorite
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A highly water-soluble phenothiazine (PTZ)–boron dipyrromethene (BODIPY)-based electron donor–acceptor dyad (WS-Probe), which contains BODIPY as the signaling antennae and PTZ as the OCl? reactive group, was designed and used as a fluorescent chemosensor for the detection of OCl?. Upon addition of incremental amounts of NaOCl, the quenched fluorescence of WS-Probe was enhanced drastically, which indicated the inhibition of reductive photoinduced electron transfer (PET) from PTZ to 1BODIPY*; the detection limit was calculated to be 26.7 nm. Selectivity studies with various reactive oxygen species, cations, and anions revealed that WS-Probe was able to detect OCl? selectively. Steady-state fluorescence studies performed at varied pH suggested that WS-Probe can detect NaOCl and exhibits maximum fluorescence in the pH range of 7 to 8, similar to physiological conditions. ESI-MS analysis and 1H NMR spectroscopy titrations showed the formation of sulfoxide as the major oxidized product upon addition of hypochlorite. More interestingly, when WS-Probe was treated with real water samples, the fluorescence response was clearly visible with tap water and disinfectant, which indicated the presence of OCl? in these samples. The in vitro cell viability assay performed with human embryonic kidney 293 (HEK 293) cells suggested that WS-probe is non-toxic up to 10 μm and implicates the use of the probe for biological applications.
- Soni, Disha,Duvva, Naresh,Badgurjar, Deepak,Roy, Tapta Kanchan,Nimesh, Surendra,Arya, Geeta,Giribabu, Lingamallu,Chitta, Raghu
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supporting information
p. 1594 - 1608
(2018/06/26)
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- BRYOSTATIN COMPOUNDS AND METHODS OF PREPARING THE SAME
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Methods for preparing a variety of bryostatin compounds are provided. The subject methods provide for preparation of bryostatin 1 in multi-gram quantities in a low and unprecedented number of convergent synthetic steps from commercially available materials. The subject methods are scalable with low estimated material costs and can provide enough material to meet clinical needs. Also provided are a variety of bryostatin analog compounds, and prodrug forms thereof, which are synthetically accessible via the subject methods and pharmaceutical compositions including the same.
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Page/Page column 80; 81
(2018/04/21)
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- With anti-bacterial activity of the piperidine link 1, 2, 3 - triazole class compound and its preparation method and application
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The present invention discloses a piperidine link 1,2,3-triazole compound with antibacterial activity and a preparation method therefor and application thereof, and belongs to the technical field of synthesis of compounds with antibacterial activity. The
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Paragraph 0100-0103
(2017/11/16)
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- PROCESS FOR CROSSED CLAISEN CONDENSATION REACTIONS PROMOTED BY LITHIUM AMIDE IN LIQUID AMMONIA
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The present invention provides a use of lithium amide in liquid ammonia as a base to produce an enolate from at least one ester starting material in a crossed Claisen condensation reaction, wherein at least one ester starting material is a β-hydroxy ester. Also provided is a method of producing lithium amide in situ for use in a crossed Claisen condensation reaction, wherein lithium is added to liquid ammonia, followed by an electron transfer agent, as well as a method of carrying out a crossed Claisen condensation reaction using an ester starting material and a β-hydroxy ester, using lithium amide in liquid ammonia produced in situ.
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Paragraph 0066-0074
(2015/07/22)
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- PROCESS FOR CROSSED CLAISEN CONDENSATION REACTIONS PROMOTED BY LITHIUM AMIDE IN LIQUID AMMONIA
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The present invention provides a use of Iithium amide in liquid ammonia as a base to produce an enolate from at least one ester starting material in a crossed Claisen condensation reaction, wherein at least one ester starting material is a β-hydroxy ester. Also provided is a method of producing lithium amide in situ for use in a crossed Claisen condensation reaction, wherein lithium is added to liquid ammonia, followed by an electron transfer agent, as well as a method of carrying out a crossed Claisen condensation reaction using an ester starting material and a β-hydroxy ester, using lithium amide in liquid ammonia produced in situ.
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Page/Page column 12
(2014/02/15)
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- Prussian blue as an efficient catalyst for rate accelerations in the transesterification of β-ketoesters
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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
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p. 1212 - 1220
(2014/04/17)
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- Selective α-amination and α-acylation of esters and amides via dual reactivity of O-acylhydroxylamines toward zinc enolates
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Selective α-amination and α-acylation of esters and amides have been developed, employing O-acylhydroxylamines as a dually reactive aminating and acylating reagent. Treatment of zinc enolates with O-acylhydroxylamines provides solely 1,3-dicarbonyl compounds under mild conditions. Introduction of a copper catalyst into the system shifts the reactivity entirely, yielding α-amination products exclusively.
- McDonald, Stacey L.,Wang, Qiu
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supporting information
p. 2535 - 2538
(2014/03/21)
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- Manganese(II) salts as efficient catalysts for chemo selective transesterification of β-keto esters under non-conventional conditions
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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
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p. 703 - 706
(2013/02/23)
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- Organocatalyzed asymmetric synthesis of morphans
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A general effective organocatalyzed synthesis of enantioenriched morphans with up to 92% ee was developed. The morphan scaffold was constructed in a one-pot tandem asymmetric organocatalyzed Michael addition followed by a domino Robinson annulation/aza-Michael intramolecular reaction sequence from easily available starting materials.
- Bradshaw, Ben,Parra, Claudio,Bonjoch, Josep
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supporting information
p. 2458 - 2461
(2013/06/27)
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- An efficient synthesis of β-ketoesters via transesterification and its application in Biginelli reaction under solvent-free, catalyst-free conditions
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A simple and efficient transesterification process for the synthesis of β-ketoester derivatives has been achieved by the reaction of methyl β-ketoester with higher alcohols at 110 C under solvent-free, catalyst-free conditions and its application in synthesis of 3,4-dihydropyrimidin-2(1H)-ones C-5 ester derivatives via Biginelli reaction has been described.
- Dharma Rao,Acharya,Kaushik
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supporting information
p. 6644 - 6647
(2013/11/19)
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- AgOTf-catalyzed transesterification of β-keto esters
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AgOTf proved to be an effective catalyst for the transesterification of β-keto esters with primary, secondary and tertiary alcohols. The products were obtained in high yield within a reasonable reaction time period. The kinetics of the transesterification reaction were also studied and the reaction was found to follow second-order kinetics. Copyright
- Das, Rima,Chakraborty, Debashis
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experimental part
p. 140 - 144
(2012/05/20)
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- Design and synthesis of new 1,4-dihydropyridines containing 4(5)-chloro-5(4)-imidazolyl substituent as a novel calcium channel blocker
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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
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scheme or table
p. 1417 - 1426
(2012/05/04)
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- Efficient trans-acetoacylation mediated by ytterbium(III) triflate as a catalyst under solvent-free condition
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A simple and efficient trans-acetoacylation method for the synthesis of β-keto ester derivatives has been described using ytterbium(III) triflate as a new catalyst under solvent-free condition. This method was found to be efficient and convenient for the synthesis of a wide variety of β-keto ester derivatives.
- Dharma Rao,Kaushik
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experimental part
p. 5104 - 5106
(2011/10/08)
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- Molecular iodine in ionic liquid: A green catalytic system for esterification and transesterification
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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
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scheme or table
p. 1670 - 1676
(2010/08/03)
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- Mild and high-yielding synthesis of β-keto esters and β-ketoamides
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In the presence of sodium acetate, the reaction between 2,2,6-trimethyl-4H-1,3-dioxin-4-one and secondary or tertiary alcohols (including chiral ones) or primary or secondary amines could be carried out in refluxing tetrahydrofuran, under much milder conditions than those described in the literature. In these new conditions, side products normally observed using the traditional protocol were avoided, and-keto esters and-ketoamides were normally obtained in quantitative yields.
- Sridharan, Vellaisamy,Ruiz, Miriam,Menendez, J. Carlos
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experimental part
p. 1053 - 1057
(2010/06/16)
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- Hexamethylenetetramine-mediated transesterification of β-keto esters
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Treatment of methyl or ethyl β-keto esters with primary, secondary, or tertiary alcohols in the presence of a catalytic amount of hexamethylenetetramine results in good to high yields of the corresponding esters. Georg Thieme Verlag Stuttgart.
- Ribeiro, Rodrigo S.,De Souza, Rodrigo O. M. A.,Vasconcellos, Mario L. A. A.,Oliveira, Bianca L.,Ferreira, Leonardo C.,Aguiar, Lucia C. S.
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- 3-Nitrobenzeneboronic acid as an efficient and environmentally benign catalyst for the selective transesterification of β-keto esters
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An efficient and high-yielding procedure for the selective transesterification of various β-keto esters using 3-nitrobenzeneboronic acid as a catalyst in an environmentally acceptable process is described. Georg Thieme Verlag Stuttgart.
- Tale,Sagar,Santan,Adude
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p. 415 - 418
(2007/10/03)
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- Facile and selective transesterification of β-keto esters using NaIO4, KIO4, and anhydrous CaCl2 as inexpensive catalysts under neutral conditions
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NaIO4, KIO4 and anhydrous CaCl2 catalyzed selective transesterification of β-keto esters is described. Neutral reaction conditions and inexpensive catalysts are important features of this method.
- Bandgar, Babasaheb P.,Hashmi, Arshad M.,Pandit, Shivaji S.
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p. 1101 - 1104
(2007/10/03)
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- Niobium(V) oxide: A new and efficient catalyst for the transesterification of β-keto esters
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Niobium(V) oxide is an efficient catalyst for the transesterification of β-keto esters with several kinds of alcohols, leading to good conversions. Moderate to good isolated product yields have been obtained at faster rates than those recently reported for various catalysts.
- De Sairre, Mirela Inês,Bronze-Uhle, érika Soares,Donate, Paulo Marcos
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p. 2705 - 2708
(2007/10/03)
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- Lipophilic 4-imidazoly-1,4-dihydropyridines: Synthesis, calcium channel antagonist activity and protection against pentylenetetrazole-induced seizure
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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
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p. 261 - 269
(2007/10/03)
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- Method for preparing chiral diphosphines
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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.
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- Ionic liquid-regulated sulfamic acid: Chemoselective catalyst for the transesterification of β-ketoesters
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1-Propyl-3-methylimidazolium chloride ([C3MIm]Cl) ionic liquid and sulfamic acid (NH2SO3H), as a synergetic catalytic medium, were used for the transesterification of acetoacetate with alcohols of different structures. It shows the good ability for the chemoselective transesterificatin of β-ketoesters and maintains its catalytic activity in the reuse.
- Bo, Wang,Ming, Yang Li,Shuan, Suo Ji
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p. 5037 - 5039
(2007/10/03)
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- Process for the transesterification of keto esters using solid acids as catalysts
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A process for the transesterification of keto esters and alcohols in approximately stoichiometric amounts using a solid acid catalyst. Solid acid catalysts may be sulfated zirconia, sulfated tin oxide, sulfated titania, sulfated iron oxide, heteropoly acids, acidic clays, acidic zeolites, or any other solid acids with high acidity or super acidity, with or without dopants. One equivalent or more of keto ester, one equivalent or more of alcohol, the solid acid catalyst, and an appropriate solvent are mixed and heated to 70 to 120° C. at atmospheric or reduced pressure to furnish the keto transester in high yields.
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- Chemoselective transesterification of β-keto esters under neutral conditions using NBS as a catalyst
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Facile and selective transesterification of β-keto esters using N-bromosuccinimide (NBS) as an efficient and neutral catalyst is described.
- Bandgar,Uppalla,Sadavarte
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p. 1715 - 1718
(2007/10/03)
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- Metal salts as novel catalysts for efficient transesterification of β-ketoesters
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Ethyl/methyl β-ketoesters with alcohols in presence of catalytic amount of anhydrous metal salts (FeSO4, CuSO4) undergo smooth transesterification.
- Bandgar,Sadavarte,Uppalla
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p. 2063 - 2066
(2007/10/03)
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- Palladium-catalyzed α-arylation of esters
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A new and simple one-pot procedure for the palladium-catalyzed intermolecular α-arylation of esters is described. A number of esters can be functionalized with a wide range of aryl bromides using Pd(OAc)2 or Pd2(dba)3 and
- Moradi,Buchwald
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p. 7996 - 8002
(2007/10/03)
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- Zn mediated transesterification of β-ketoesters
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Methyl/ethyl β-ketoesters when treated with various alcohols along with catalytic amount of Zn dust in refluxing toluene undergo smooth transesterification.
- Bandgar,Sadavarte,Uppalla
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- Liquid oligomers containing acrylate unsaturation
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The liquid oligomeric compositions of this invention are made by the Michael addition reaction of acetoacetate functional donor compounds with multifunctional acrylate receptor compounds where the equivalent ratios of multifunctional acrylate to acetoacetate vary from >/=1:1 to >/=13.2:1 depending on the functionality of both multifunctional acrylate and acetoacetate. Unuseable gelled or solid oligomer products occur below the claimed ranges. The liquid oligomers of this invention are further crosslinked to make coatings, laminates and adhesives.
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- Asymmetric hydrogenation method of a ketonic compound and derivative
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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
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- Solvent-free microwave-assisted organic reactions prepation of β-keto esters
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Microwave technique has been utilised in the preparation of β-keto esters. Two different procedures are described: transesterification of β- keto esters and ring opening of 2,2,6-trimethyl-1,3-dioxin-4-one.
- Gianotti, Massimo,Martelli, Giorgio,Spunta, Giuseppe,Campana, Eileen,Panunrio, Mauro,Mendozza, Monica
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p. 1725 - 1730
(2007/10/03)
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- A facile and selective procedure for transesterification of β-keto esters promoted by yttria-zirconia based lewis acid catalyst
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An yttria-zirconia based strong Lewis acid efficiently catalyses the transesterification of β-keto esters under environmentally safe, heterogeneous reaction conditions with high selectivity and in good to excellent yields.
- Kumar, Pradeep,Kumar Pandey, Rajesh
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p. 251 - 253
(2007/10/03)
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- Decarboxylative elimination of enol triflates as a general synthesis of acetylenes
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Decarboxylative elimination of a range of enol triflates of β-keto esters gives acetylenes.
- Fleming, Ian,Ramarao, Chandrashekar
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p. 1113 - 1114
(2007/10/03)
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- 3-carboalkoxy-2, 3-dihydro-1H-phenothiazin-4[10H]-one derivatives
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Phenothiazines of the formula: STR1 where R1 is H or --COOR, where R is selected from the group consisting of branched or unbranched alkyl groups containing from 1 to 4 carbon atoms, and where X is selected from H, branched or unbranched alkyl groups containing from 1 to 4 carbons, and halogen, and pharmaceutically acceptable salts thereof. Particularly preferred phenothiazines are those wherein X is hydrogen, chloro, bromo or methyl, R1 is COOR, and R is methyl, ethyl or t-butyl.
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- Synthesis and calcium-channel antagonist activity of 4-imidazolyl-1,4-dihydropyridines
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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
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p. 165 - 168
(2007/10/03)
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- The stereoselective preparation of β-hydroxy esters using a yeast reduction in an organic solvent
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A range of (S)-β-hydroxy esters has been prepared in high yield (56-96%) and with very high enantioselectivity (>94%) using a yeast mediated reduction in light petroleum. It was found that the ester functionality had a marked effect on both the isolated yield and the quantity of yeast required to effect complete reduction.
- Medson, Caroline,Smallridge, Andrew J.,Trewhella, Maurie A.
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p. 1049 - 1054
(2007/10/03)
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- New method of zinc activation by electrochemistry: synthetic applications to the Blaise reaction
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A new electrochemical zinc metal activation method based on the cathodic reduction of a catalytic amount of zinc bromide in the presence of a zinc anode is described.This procedure is applied to the coupling of α-bromoesters with nitriles, and affords β-ketoesters in good yield.
- Zylber, N.,Zylber, J.,Rollin, Y.,Dunach, E.,Perichon, J.
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- A Study of the Ferrous Ion-initiated SRN1 Reactions of Halogenoarenes with tert-Butyl Acetate and N-Acylmorpholine Enolates
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A detailed preparative study is reported of the ferrous ion-initiated SRN1 reactions of a range of halogenoarenes with the sodium enolates of tert-butyl acetate, n-acetylmorpholine and a number of higher N-acylmorpholines.Smooth and rapid substitution occurs in many cases, and good to excellent yields were obtained of arylacetic esters or acids, arylacetamides and arylalkanamides.The broad scope and limitations of the process have been defined, and the possible role of the ferrous ion is discussed.
- Leeuwen, Milko van,McKillop, Alexander
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p. 2433 - 2440
(2007/10/02)
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- Method for production of t-butyl 3-oxobutyrates and their use
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Disclosed are an advantageous method of industrial production of tert-butyl 3-oxobutylate, which is a useful intermediate for synthesis, characterized by reacting tert-butyl alcohol with diketene in the presence of 4-(tertiary amino) pyridine, and an industrially advantageous method of producing cephalosporin compounds or pharmaceutically acceptable salts thereof, using tert-butyl 3-oxobutylate as an intermediate.
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- Phase Transfer Generation of Acyltetracarbonyliron Anions: their Role in the Phase Transfer Carbonylation of Reactive Halides to give Carboxylic Acids and Symmetrical and Unsymmetrical Ketones
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Acyltetracarbonyliron anions RCOFe(CO)4(1-) (3) are readily synthesised under mild phase transfer (PT) conditions from pentacarbonyliron and reactive organic halides; the in situ generated anions (3) (R = ArCH2) are the true catalysts in the PT carbonylation of benzyl halides to give ketones or carboxylic acids.
- Laurent, Pascale,Tanguy, Guy,Abbayes, Herve des
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p. 1754 - 1756
(2007/10/02)
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