- Enamine Organocatalysts for the Thiol-Michael Addition Reaction and Cross-Linking Polymerizations
-
This article describes an efficient enamine organocatalyzed thiol-Michael click reaction and its broad application in cross-linking polymerizations. A series of enamines was shown to catalyze the thiol-Michael reaction via a nucleophilic pathway. By varying the amines as well as the ring size of the ketones, enamines were designed with broad ranges of nucleophilic character ranging from 11 to 17 on the Mayr nucleophilicity scale. Upon evaluating the enamines' organocatalytic effect on the kinetics of reactions involving a thiol and Michael acceptor, wherein butyl 3-mercaptopropionate and 1-hexyl acrylate were used as model reactants, enamines were shown to outperform their base analogs. The efficiency and overall reaction yields, ranging from 11 to 92% based on the thiol conversion, were highly dependent upon the nucleophilicity of the enamines employed. Interestingly, in situ formation of an enamine via photo-deprotection of an amine in the presence of cyclic ketones facilitated the thiol-Michael reaction efficiently while simultaneously enabling higher functional group conversion. This efficiency in the reaction kinetics and conversion was extended to multifunctional derivatives, which resulted in the formation of highly cross-linked polymers.
- Sinha, Jasmine,Soars, Shafer,Bowman, Christopher N.
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p. 1693 - 1701
(2021/02/16)
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- Synthesis of Medium-Sized Carbocycles via a Bidentate Lewis Acid-Catalyzed Inverse Electron-Demand Diels-Alder Reaction Followed by Photoinduced Ring-Opening
-
The combination of a Lewis acid-catalyzed inverse electron-demand Diels-Alder (IEDDA) reaction with a photoinduced ring-opening (PIRO) reaction in a domino process has been established as an efficient synthetic method to access medium-sized carbocycles. From readily available electron-rich and electron-poor phthalazines and enamines, respectively, as starting materials, various 9- and 11-membered carbocycles were prepared. This versatile transition-metal-free tool will be valuable for broadening the structural space in biologically active compounds and functional materials.
- Ruhl, Julia,Ahles, Sebastian,Strauss, Marcel A.,Leonhardt, Christopher M.,Wegner, Hermann A.
-
supporting information
p. 2089 - 2093
(2021/04/05)
-
- 1 microwave-induced montmorillonite-mediated facile synthesis of enamines
-
Montmorillonite clay-mediated simple and high yielding protocol for the synthesis of various enamines with secondary amines and ketones is developed under microwave condition. This protocol is very convenient to accesses the enamines from cyclic amines with various carbonyl compounds in high yield under mild reaction conditions with short reaction time.
- Yadav, Ram Naresh,Banik, Indrani,Srivastava, Ashok Kumar,Ramos, Katherine,Banik, Bimal Krishna
-
p. 249 - 254
(2020/01/08)
-
- Revisiting the role of acids and hydrogen bond acceptors in enamine formation
-
A systematic investigation into the effects of acids and hydrogen bond acceptors on the reaction rates and equilibria of enamine formation is reported. Acids can accelerate the reaction but do not change the reaction equilibria. In comparison, hydrogen bond acceptors facilitate the enamine formation via their strong hydrogen bonding interaction with the water generated in the reaction.
- Hammond, Gerald B.,Lu, Zhichao,Xu, Bo
-
supporting information
p. 6849 - 6852
(2020/10/02)
-
- Preparation of Hexahydrocarbazole Derivatives by Reductive Indolization
-
The reductive indolization is a two-step protocol performed in one flask: First, the acid-mediated Fischer indolization of a cyclic ketone with phenylhydrazine forms an iminium ion which is subsequently reduced by a hydrido borate reagent to the indoline as the final product. We utilized this new strategy for the preparation of hexahydrocarbazole derivatives with a side chain in the quaternary C4a-position. Starting materials were several N1- and aryl-substituted phenylhydrazines and a cyclic ketone with propanoic ester moiety, which is the product of the conjugated addition of cyclohexanone to ethyl acrylate. Furthermore, benzannulated congeners as well as a pyrido[4,3-b]indole derivative were accessed. The hexahydrocarbazole defines a molecular scaffold with two points of diversification. Therefore, several derivatives at N9 and at the C4a-side chain were prepared.
- Christoffers, Jens,Dierks, Anna,Fliegel, Lukas,Schmidtmann, Marc
-
p. 7164 - 7175
(2020/11/30)
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- Tf2O-Mediated Intermolecular Coupling of Secondary Amides with Enamines or Ketones: A Versatile and Direct Access to β-Enaminones
-
Based on the Tf2O-mediated intermolecular reaction of secondary amides with enamines derived from ketones, a novel approach to β-enaminones has been developed. The reaction is widely functional group tolerant and highly chemoselective. In the presence of 4 ? molecular sieves, the method can be extended to the one-pot condensation of secondary amides with ketones for NH β-enaminones synthesis.
- Liu, Yong-Peng,Zhu, Cheng-Jie,Yu, Cun-Cun,Wang, Ai-E,Huang, Pei-Qiang
-
supporting information
p. 7169 - 7174
(2019/11/16)
-
- Enantioselective Electrochemical Lactonization Using Chiral Iodoarenes as Mediators
-
The enantioselective electrochemical lactonization of diketo acid derivatives using chiral iodoarenes as redox mediators is reported for the first time. Good to high stereoselectivities are observed in the lactonization and also in intermolecular α-alkoxylations of diketo ester derivatives. This enantioselective process was then adapted to an electrochemical flow microreactor where only small amounts of supporting electrolyte were necessary.
- Gao, Wen-Chao,Xiong, Zi-Yue,Pirhaghani, Shafigh,Wirth, Thomas
-
supporting information
p. 276 - 284
(2019/01/04)
-
- Palladium-Catalysed Construction of All-Carbon Quaternary Centres with Propargylic Electrophiles: Challenges in the Simultaneous Control of Regio-, Chemo- and Enantioselectivity
-
This article describes the palladium-catalysed three-component coupling of 1,3-dicarbonyl compounds with nucleophiles and propargylic electrophiles for the generation of quaternary all-carbon centres in a single step, which necessitates the simultaneous control of regio-, chemo- and enantioselectivity. The use of propargyl enol carbonates, the source of two of the components, was found to be essential in maintaining high levels of regiocontrol and chemoselectivity, whereas a careful analysis of p K a trends of O-, C- and N-nucleophiles as the other coupling partner indicates that the highest levels of selectivity are likely to be obtained with relatively acidic species, such as phenols, 1,3-dicarbonyl compounds and aromatic N-heterocycles. Finally, studies towards the development of the catalytic enantioselective construction of quaternary all-carbon centres by means of alkenylation and allylic alkylation are disclosed.
- Kenny, Miles,Schr?der, Sybrin P.,Taylor, Nicholas J.,Jackson, Paula,Kitson, Daniel J.,Franckevi?ius, Vilius
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p. 1796 - 1814
(2018/04/05)
-
- Divergent pathways to isophthalates and naphthalate esters from methyl coumalate
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Methyl coumalate readily reacts with enamines at ambient temperature to give lactones, which can be further transformed into isophthalates and tetrahydronaphthoates. Both cyclic and acyclic enamines show good reactivity. Dehydrogenation of tetrahydronaphthoate 4a was achieved on a hundred-gram scale.
- Yu, Huangchao,Kraus, George A.
-
supporting information
p. 4008 - 4010
(2018/10/04)
-
- SPIROFURANONE COMPOUNDS, DERIVATIVES THEREOF AND PROCESSES FOR THEIR PREPARATION
-
The present invention provides compounds comprising fused tricyclic backbone structure and processes for their preparation. The invention further provides compounds and compositions useful in the treatment of pain and any type of disorder or symptom associated therewith.
- -
-
Page/Page column 40; 41
(2016/08/23)
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- Regio- and stereoselective synthesis of chiral nitrilolactones using Baeyer–Villiger monooxygenases
-
This work describes the regio- and enantioselective synthesis of nitrile-containing chiral lactones from easily accessible ketone precursors using Baeyer–Villiger monooxygenases. These biocatalysts controlled the distribution of regioisomers much more tightly than commonly used stoichiometric reagents, additionally with good to excellent optical purity of products. A surprising case of strong stereoelectronic control was also observed. We tested a library of 14 catalysts using five-to eight-membered cyclic ketones with two different tether lengths to the nitrile group. In all but the largest series we found suitable wild-type enzymes for preparative scale synthesis of the target compounds. The diverse possibilities to further functionalize lactones and nitriles make this method interesting for the generation of chiral building blocks.
- Fink, Michael J.,Snajdrova, Radka,Winninger, Alexander,Mihovilovic, Marko D.
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p. 7241 - 7248
(2016/10/26)
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- SUBSTITUTED HETEROCYCLIC AMINE DERIVATIVES AS MULTIKINASE INHIBITORS FOR THE TREATMENT OF CANCER
-
The present invention relates to compounds of formula (I), their isotopic forms, stereoisomeric forms, tautomeric forms, pharmaceutically acceptable salts, pharmaceutically acceptable solvates, prodrugs, polymorphs or N-oxides thereof. The present invention also relates to processes for the preparation of compounds of formula (I) and pharmaceutical compositions comprising the compounds of formula (I). The compounds and their pharmaceutical compositions are multikinase inhibitors and are useful in the treatment of proliferative disorders, such as cancers.
- -
-
Page/Page column 90
(2015/09/28)
-
- Silver-free activation of ligated gold(I) chlorides: The use of [Me3NB12Cl11]- as a weakly coordinating anion in homogeneous gold catalysis
-
Phosphane and N-heterocyclic carbene ligated gold(I) chlorides can be effectively activated by Na[Me3NB12Cl11] (1) under silver-free conditions. This activation method with a weakly coordinating closo-dodecaborate anion was shown to be suitable for a large variety of reactions known to be catalyzed by homogeneous gold species, ranging from carbocyclizations to heterocyclizations. Additionally, the capability of 1 in a previously unknown conversion of 5-silyloxy-1,6-allenynes was demonstrated.
- Wegener, Michael,Huber, Florian,Bolli, Christoph,Jenne, Carsten,Kirsch, Stefan F.
-
supporting information
p. 1328 - 1336
(2015/02/05)
-
- Importance of the Electron Correlation and Dispersion Corrections in Calculations Involving Enamines, Hemiaminals, and Aminals. Comparison of B3LYP, M06-2X, MP2, and CCSD Results with Experimental Data
-
While B3LYP, M06-2X, and MP2 calculations predict the δG° values for exchange equilibria between enamines and ketones with similar acceptable accuracy, the M06-2X/6-311+G(d,p) and MP2/6-311+G(d,p) methods are required for enamine formation reactions (for example, for enamine 5a, arising from 3-methylbutanal and pyrrolidine). Stronger disagreement was observed when calculated energies of hemiaminals (N,O-acetals) and aminals (N,N-acetals) were compared with experimental equilibrium constants, which are reported here for the first time. Although it is known that the B3LYP method does not provide a good description of the London dispersion forces, while M06-2X and MP2 may overestimate them, it is shown here how large the gaps are and that at least single-point calculations at the CCSD(T)/6-31+G(d) level should be used for these reaction intermediates; CCSD(T)/6-31+G(d) and CCSD(T)/6-311+G(d,p) calculations afford δG° values in some cases quite close to MP2/6-311+G(d,p) while in others closer to M06-2X/6-311+G(d,p). The effect of solvents is similarly predicted by the SMD, CPCM, and IEFPCM approaches (with energy differences below 1 kcal/mol).
- Castro-Alvarez, Alejandro,Carneros, Héctor,Sánchez, Dani,Vilarrasa, Jaume
-
p. 11977 - 11985
(2016/01/09)
-
- HETEROARYL COMPOUNDS AND METHODS OF USE THEREOF
-
Provided herein are thiophene compounds, methods of their synthesis, pharmaceutical compositions comprising the compounds, and methods of their use. The compounds provided herein are useful for the treatment, prevention, and/or management of various neurological disorders, including but not limited to, psychosis and schizophrenia.
- -
-
Page/Page column 77
(2013/08/28)
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- PARASITICIDAL DIHYDROISOXAZOLE COMPOUNDS
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Provided are dihydroisoxazole compounds I useful for controlling parasites both in animals and agriculture. Further provided are methods for controlling parasite infestations of an animal by administering an effective amount of a compound as described above, or a pharmaceutically acceptable salt thereof, to an animal, as well as formulations for controlling parasite infestations using the compounds described above or an acceptable salt thereof, and an acceptable carrier. Also provided are compounds and processes useful for making the dihydroisoxazole compounds.
- -
-
Page/Page column 71
(2012/12/13)
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- PARASITICIDAL COMPOUNDS, METHODS, AND FORMULATIONS
-
Provided are dihydroisoxazole compounds useful for controlling parasites both in animals and agriculture. Further provided are methods for controlling parasite infestations of an animal by administering an effective amount of a compound as described above, or a pharmaceutically acceptable salt thereof, to an animal, as well as formulations for controlling parasite infestations using the compounds described above or an acceptable salt thereof, and an acceptable carrier. Also provided are compounds and processes useful for making the dihydroisoxazole compounds.
- -
-
Page/Page column 71
(2012/12/13)
-
- Synthesis of 6 H-dibenzo[ b, d ]pyran-6-ones using the inverse electron demand Diels-Alder reaction
-
A set of coumarin-fused electron-deficient 1,3-dienes was synthesized, which differ in the nature of the electron-withdrawing group (EWG) at the terminus of the diene unit and (when EWG = CO2Me) the nature and position of substituents. These dienes reacted with the enamine derived from cyclopentanone and pyrrolidine to afford the corresponding cyclopenteno-fused 6H-dibenzo[b,d]pyran-6-ones, most likely via a domino inverse electron demand Diels-Alder (IEDDA)/elimination/transfer hydrogenation sequence. The parent diene (EWG = CO2Me, no substituents) was reacted with a range of electron-rich dienophiles (mostly enamines) to afford the corresponding 6H-dibenzo[b,d]pyran-6-ones or their nondehydrogenated precursors, which were aromatized upon treatment with a suitable oxidant. The enamines could either be synthesized prior to the reaction or generated in situ. The syntheses of 30 dibenzopyranones are reported.
- Pottie, Ian R.,Nandaluru, Penchal Reddy,Benoit, Wendy L.,Miller, David O.,Dawe, Louise N.,Bodwell, Graham J.
-
experimental part
p. 9015 - 9030
(2011/12/03)
-
- Enamines: efficient nucleophiles for the palladium-catalyzed asymmetric allylic alkylation
-
Enamines were tested to be efficient nucleophiles for palladium-catalyzed asymmetric allylic alkylation, avoiding the use of unstablilized ketone enolates formed by strong bases. The influence of the chiral metallocene-based ligands upon this reaction was studied in detail. It was shown that planar chirality played an important role in enantioselectivities. Meanwhile, different kinds of enamines and allylic acetate to the reactions were also investigated. High catalytic activity and excellent enantioselectivity (up to 99% ee) were obtained with pyrrolidine enamines of both aliphatic and aromatic ketone.
- Zhao, Xiaohu,Liu, Delong,Xie, Fang,Zhang, Wanbin
-
experimental part
p. 512 - 517
(2009/04/07)
-
- Reaction control in synthetic organic photochemistry: Switching between [5+2] and [2+2] Modes of Cycloaddition
-
Split personality: Reaction conditions that enable powerful control over the mode of photocycloaddition in maleimides have been developed. Direct irradiation favors the [5+2] mode whereas sensitized irradiation allows a complete switch to the [2+2] mode (see scheme; TBS=tertbutyldimethylsilyl).
- Roscini, Claudio,Cubbage, Kara L.,Berry, Malcolm,Orr-Ewing, Andrew J.,Booker-Milburn, Kevin I.
-
supporting information; experimental part
p. 8716 - 8720
(2010/03/01)
-
- New, general, and practical enamine cyclopropanation using dichloromethane
-
Dichloromethane serves as a novel electrophilic carbene equivalent which adds to an enamine double bond. The presence of other alkene moieties in the enamine partner is well tolerated. Even enamines derived from sterically hindered ketones react readily with dichloromethane promoted by TiCl 4-Mg.
- Tsai, Chia-Chung,Hsieh, I.-Lin,Cheng, Tsung-Ting,Tsai, Ping-Kuei,Lin, Kuo-Wei,Yan, Tu-Hsin
-
p. 2261 - 2263
(2007/10/03)
-
- A NOVEL SYNTHESIS OF 2-AZABICYCLIC-3-CARBOXYLIC ACIDS, USEFUL AS IMPORTANT DRUG INTERMEDIATES
-
A novel process for the preparation of 2-azabicyclo-3-carboxylic acid hydrochloride of formula (I), by reacting the compound of formula (II) with an acylating agent in a non-polar solvent at 0-150 °C to give a compound of formula (III), which is reacted with an enamine of formula (IV) in a non-polar solvent in the presence of an organic base at 0 °C to 150 °C to yield a compound of formula (V), which is hydrolytically cyclised to give a compound of formula (VI) and further catalytically hydrogenated to give the compound of formula (I).
- -
-
Page/Page column 7
(2008/06/13)
-
- Construction of fused cyclooctanoid ring systems via seven-membered ring carbonyl ylides
-
A series of α-diazo carbonyl compounds tethered to cyclopentanone/cyclohexanone/1-tetralone units have been synthesized using a diazomethane solution to construct various fused cyclooctane ring systems via rhodium-generated carbonyl ylides. The reaction of rhodium(II) acetate dimer with various α-diazo carbonyl compounds generated transient cyclic seven-membered ring carbonyl ylides, which underwent facile 1,3-dipolar cycloadditions with dipolarophiles, like N-phenylmaleimide, p-benzoquinone, and DMAD to furnish a variety of fused epoxy-bridged cyclooctane ring systems in a tandem manner. Interestingly, an oxepine ring system was generated via an intramolecular proton transfer of a seven-membered ring carbonyl ylide. A tri-oxa polycyclic compound was obtained in the case of p-benzoquinone as dipolarophile. A single-crystal X-ray analysis of a fused cyclootanoid derivative is reported to decisively establish the structure and stereochemistry of the fused epoxy-bridged cyclooctane ring systems; a further analysis revealed the existence of a unique intermolecular C-H ···π interaction motif in the solid-state architecture.
- Muthusamy, Sengodagounder,Babu, Srinivasarao Arulananda,Gunanathan, Chidambaram,Suresh, Eringathodi,Dastidar, Parthasarathi
-
p. 801 - 811
(2007/10/03)
-
- Formation of aromatic rings through enamine annulation
-
(matrix presented) Condensation of pyrrolidine enamine of ketones with 1,4-diacetoxy-2-butanone provides a new, concise synthetic route to substituted benzenes, dihydroindenes, tetrahydronaphthalenes, and di- and octahydrophenanthrenes. The reaction produced modest yields with regiocontrol of the secondary amine substituent.
- Wang, Chen,Kohn, Harold
-
p. 1773 - 1775
(2007/10/03)
-
- Acid catalysed reactions of 5-formyluracils with enamines. A facile synthesis of 5-acylvinyluracils
-
5-Formyl-1,3-dimethyluracil (1) reacts with secondary amine derived enamines of ketones and aldehydes to provide 5-(acyvinyl)uracil derivatives. The presence of a CH3 group at C-6 of 1 induces a competitive annulation reaction. Depending on the bulk of substituents 5-(acylvinyl)-uracils acquire cis -diene and E or Z configurations on the vinyl unit. Enamines derived from 1,3-cyclohexanedione and ethyl acetoacetate react with 1 in 1: 2 stoichiometric manner to provide 5-(9-xanthenyl)uracil and 5-(6- cycohexadienyl)uracil (X-ray) derivatives.
- Singh, Harjit,Dolly,Hundal, Maninder Singh,Hundal, Geeta,Singh, Palwinder,Chimni, Swapandeep Singh,Kumar, Subodh
-
p. 7563 - 7572
(2007/10/03)
-
- On the formation and reactivity of 2-alkylidene-benzopyrans and their 2-amino-5,6-benzo-2H-pyran precursors
-
A series of 2-amino-substituted 5,6-benzo-2H-pyrans 14, 2-alkylidene-5,6-benzo-2H-pyrans 15, and their dimers 17 are obtained, depending on the condition used, by the reaction of 2-hydroxy-benzaldehydes 1 with enamines 9 derived of (cyclo)aliphatic ketones. Compounds 14, 15, and 17 can be transformed into 2-alkyl-benzopyrylium salts 16 or 2-[1-(2-hydroxyphenyl)-alken-2-yl]-benzopyrylium salts 23 by treatment with mineral acids. With aromatic aldehydes or the Vilsmeier reagent the compounds 14, 15, or 17 are transformed into deeply colored 2-(aryl-alkenyl)-benzopyrylium perchlorates 25 or 2-(2-dialkylamino)-alkenyl-benzopyrylium salts 26, respectively. Johann Ambrosius Barth 1998.
- Kanitz, Andreas,Hartmann, Horst,Czerney, Peter
-
-
- Synthesis and antiinflammatory activity of certain 5,6,7,8- tetrahydroquinolines and related compounds
-
Modification of some 8-benzylidene-5,6,7,8-tetrahydroquinolines, which have good antiulcer activity, led to three distinct classes of compounds with good in vivo antiinflammatory activity. Initial efforts led to a series of alkenes derived from 5,6,7,8-tetrahydroquinolines substituted at the 8- position. A second approach concentrated on replacing the CH linkage of these 8-benzylidene-substituted compounds with other spacer groups and increasing the size of the cycloalkyl ring from a six- to seven-membered ring, which provided 6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine analogues. Finally, the substituent was switched from the cycloalkyl ring to the 2-position of the pyridine ring. Variation of the 2-substituent was also examined. Optimal antiinflammatory activity after oral administration was found in both the rat carrageenan paw edema and rat developing adjuvant arthritis models with 2- substituted 6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridines, and of particular interest was 27 (WY-28342).
- Calhoun,Carlson,Crossley,Datko,Dietrich,Heatherington,Marshall,Meade,Opalko,Shepherd
-
p. 1473 - 1481
(2007/10/02)
-
- Synthesis and structure-activity relationships of juvenoids derived from 2-(4-hydroxybenzyl)cycloalkan-1-ones
-
Juvenoids 16-30, 32, 36, 38-41, 44-46, and 49-56 containing carbamate, carbonate, and urea moieties in the molecule were synthesized and subjected to a biological screening. Carbamate juvenoids 1-4 were used as reference compounds for a detailed structure-activity study of their analogues. A clear relationship between the nature of the side chain functional group and the biological activity was found. Surprisingly, not only the juvenoids 1,4 but also 38-41, the compounds with a reversed carbamate N,O-substitution pattern, showed very promising biological activity. In contrast, the carbonate and urea derivatives displayed a remarkably low activity. The relationship between the size and substitution at atoms C(2) and C(3) of the saturated ring and the biological activity is very complex and is still not completely understood.
- Rejzek,Wimmer,Saman,Ricankova,Nemec
-
p. 1241 - 1255
(2007/10/02)
-
- Reductive Cyclization of Ketones Tethered to Activated Olefins Mediated by Magnesium in Methanol
-
The reductive cyclization of various ketones tethered to activated olefins such as α,β-unsaturated esters, nitriles, sulfoxides, and sulfides mediated by magnesium in dry methanol in the presence of mercuric chloride.When traeted with magnesium in dry methanol at -23 deg C all of the ketones except nitrile 9 (42percent) and 5-oxa-8-keto-2-enoate 5 (13percent) gave excellent yields (79-98percent) of mono- and bicyclic alcohol products resulting from carbon-carbon bond formation between the β-carbon of the activated olefin and the carbonyl carbon.The reaction was accelerated by the catalytic amount of mercuric chloride, although the stereoselectivity was not affected by the catalyst.For all the substrates except 8-keto-2-enoate 3 and 5-aza-8-keto-2-enoate 6, the configuration of the major product was trans between the hydroxy and (methoxycarbonyl)methyl groups.The product isomer ratios were independent of the substrate geometry (E or Z).In contrast to the ketones, aldehydes tethered to α,β-unsaturated esters gave products of simple reduction of the double bond and/or saturated alcohols instead of the cyclized products.When the reaction temperature was lowered, the yields of cyclized product were significantly affected by the production of appreciable amounts of saturated product, but the stereoselectivity was not improved.Under the same reaction conditions α,β-unsaturated sulfoxide 16 gave deoxygenated sulfide 18 (85percent) as the major product along with a small amount (9percent) of cyclized product 19t.In contrast, sulfone 17 underwent desulfonylation instead of cyclization to give olefin 20 (54percent).With excess magnesium (15 equiv), however, α,β-unsaturated sulfoxide 16 gave cyclized sulfide 19t (95percent) via deoxygenated sulfide 18.Both 16Z and 16E afforded product 19t as a single isomer.It is suggested that the reductive cyclization of the α,β-unsaturated esters and nitriles proceed by means of nucleophilic attack of a β-carbon radical anion, formed by initial electron transfer from magnesium metal to the activated olefin, on the carbonyl group.The cyclization of the α,β-unsaturated sulfide proceeds by nucleophilic attack of the ketyl on the olefinic double bond.
- Lee, Ge Hyeong,Choi, Eun Bok,Lee, Eun,Pak, Chwang Siek
-
p. 1428 - 1443
(2007/10/02)
-
- Regioselective Aryl Radical Cyclization. 1. Stereocontrolled Synthesis of Linearly Condensed Hydroaromatic Carbocyclic Systems through 6-endo-ring Closures
-
The stereocontrolled synthesis of trans-octahydroanthracenes 3, 11a-c, and 14a-c and trans-octahydro-5aH-cycloheptanaphthalene (27) through implementation of an efficient and highly regioselective 6-endo-trig-aryl radical cyclization of the respective 2-(o-bromoaryl)-1-methylenecyclohexanes 2, 10a-c, and 13a-c and 2-(o-bromobenzyl)-1-methylenecycloheptane (41) with tri-n-butyltin hydride id described.The radical cyclization of 2-(o-bromobenzyl)-1-methylenecyclopentane (43), in contrast, produced a mixture of the cis- and trans-hexahydro-1H-benzindenes (38) and (37).
- Pal, Sitaram,Mukhopadhyaya, Jayanta K.,Ghatak, Usha Ranjan
-
p. 2687 - 2694
(2007/10/02)
-
- Alkylation of Cycloalkanoindoles via Indolylmagnesium Salts: Synthesis of 3H-Indoles and Oxidative Rearrangement to Spiro-3'-ones
-
Alkylation of cycloalkanoindolylmagnesium iodide with alkyl halides has been analyzed to prepare cycloalkano-3H-indoles, methyl and N,N-dimethylpropyl derivatives.Spiro derivatives appear as secondary products in this reaction.Selectivity and optimization of the reaction has been determined and a mechanism for the formation of the spiro derivative is proposed.
- Rodriguez, Jose-Gonzalo,Andres, Angel San
-
p. 1293 - 1299
(2007/10/02)
-
- THE ?-BARRIER TO ROTATION IN STERICALLY UNHINDERED ENAMINES: CONFORMATIONAL STUDIES BY DYNAMIC NMR, XXXVIII
-
The ?-barriers to rotation about the enamine (N-Csp2) bond in four pyrrolidinocyclo-n-alkenes (n = 5, 6, 7, 8) have been determined, and are discussed in terms of the steric interactions between the pyrrolidine and cycloalkene rings in the ground state.Distinct barriers were determined for two different conformations of the cyclooctene ring.Barriers were determined in two acyclic N,N-(dialkylamino)cycloalkenes for reference comparison.
- Lunazzi, Lodovico,Casarini, Daniele,Anderson, J.Edgar
-
p. 217 - 221
(2007/10/02)
-
- SYNTHESIS ODS PERFLUOROCHEMICALS FOR USE AS BLOOD SUBSTITUTES. PART IV. ALACTROCHEMICAL FLUORINATION OF N-CYCLOALKYL-PYRROLIDINES AND -PIPERIDINES
-
Electrochemical fluorination of N-cyclopentylpyrrolidine gave the corresponding F-amine together with a ring-opened compound N-(F-pentyl)-F-pyrrolidine in the ratio of 1 to 1, in 55 percent yield.N-cyclohexylpyrrolidine, N-cyclopentylpiperidine and N-cyclohexylpiperidine were also electrochemically fluorinated in the same manner to give the corresponding F-amines, their isomers with rearranged structures, and ring-opened ones, in the ratio of ca. 4:2:1, 2:1:1, and 2:1:1, respectively in 51 to 53 percent yields.Supporting spectral data are presented.
- Ono, Taizo,Inoue, Yoshihisa,Arakawa, Yoshio,Naito, Youichiro,Fukaya, Chikara
-
-
- REACTIVITY OF PHENYLCARBAMOYLDIAZENE TOWARDS 1-AMINOCYCLOPENTENES
-
The reactivity of the title enamines has been studied by comparison with the corresponding cyclohexene derivatives.The enchanced electron density at the C-2 atoms leads mainly to bicyclic 1,2,4-triazin-3-one derivatives, irrespective of the amino moiety.A 1:1 enamine adduct was isolated only from 1-(morpholin-4-yl)cyclopentene.
- Benedetti, Fabio,Forchiassin, Mirella,Russo, Claudio,Nitti, Patrizia
-
p. 695 - 698
(2007/10/02)
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- 13C-1H Coupling Constants in Carbocations. 5. Trishomocyclopropenium Cations Generated from Bicyclohex-3-yl, Tricyclo2,4>oct-8-yl, and Pentacyclo2,4.03,8.05,7>non-9-yl Precursors
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One-bond 13C-H coupling constants have been measured for the trismonocyclopropenium cations derived from bicyclohex-3-yl (1), tricyclo2,4>oct-8-yl, (12, 14) and pentacyclo2,4.03,8.05,7>non-9-yl (26, 27) precursors under stable ion conditions and compared with those of the corresponding model ketones. the ΔJ values thus obtained for the bridging carbons (21-32Hz) and the ajacent methylene or methine carbons (18-27 Hz) are large and not consistent with static or equilibrating classical structures for these cations.The data provide additional confirmation of the ??-bridged, nonclassical nature of these
- Kelly, David P.,Giansiracusa, Joseph J.,Leslie, D. Ralph,McKern, Ian D.,Sinclair, Georgia C.
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p. 2497 - 2504
(2007/10/02)
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- Addition Reactions of (Phenylsulfonyl)propadiene with 1-Pyrrolidinyl Enamines of Cyclic Ketones: Syntheses and Reactions of 1,3-Dienes Possessing an Allyl Sulfone Moiety
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Addition reactions of (phenylsulfonyl)propadiene (1) with various 1-pyrrolidinyl enamines have been investigated.Allene 1 and enamines of cyclic ketones (2, 7-14) readily underwent the Michael-type addition reactions at -50 deg C to give the adducts 3, 15-20, and/or their isomers 4 and 21-26, which apparently arose by base-catalyzed isomerization of the former.These adducts were conveniently converted into the corresponding 1,3-dienes possessing allyl sulfone moiety (28, 38-45) through allyl acetates (27, 30-37) by base-promoted (n-BuLi, -50 deg C) 1,4-elimination of acetic acid to vinyl sulfones followed by deconjugation to allyl sulfones.The synthetic versatility of these dienes was revealed by the Diels-Alder reactions with dimethyl acetylenedicarboxylate (DMAD) and alkylation reactions via α-sulfonyl carbanions.
- Hayakawa, Kenji,Takewaki, Makoto,Fujimoto, Ichiro,Kanematsu, Ken
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p. 5100 - 5105
(2007/10/02)
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- Thermal Rearrangement of 3-Methylenespirododeca-1,4,9-triene and Spirododeca-1,4,9-trien-3-one
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Introduction of a double bond into the seven-membered ring of 3-methylenespirododeca-1,4-dien-3-one (1) or spirododeca-1,4-diene (16) alters the thermal behavior of both compounds.Pyrolysis of 3-methylenespirododeca-1,4,9-triene (5) affords the isomeric hydrocarbon cis,cis-2,5-dimethylene-7-vinylbicyclonon-3-ene (11).Pyrolysis of the related ketone spirododeca-1,4,9-trien-3-one (6) gives a mixture of cis,cis-5-methylene-9-vinylbicyclo-3-nonen-2-one (21), cis,cis-5-methylene-7-vinylbicyclo-3-nonen-2-one (22), and trans,trans-2,4,5a,6,8a,8b-hexahydroacenaphthylen-5(1H)-one (23).Mechanistic rationales for these reactions are presented.
- Murray, Diane F.,Baum, Mary W.,Jones, Maitland
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- THE REACTION OF TRICHLOROSILANE WITH ENAMINES
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A previously unknown reaction of trichlorosilane with enamines has been discovered and a preliminary study done on the possible mechanism.The products of the reaction are a regiospecific trichlorosilyl adduct resulting from addition of the trichlorosilane to the enamine unsaturation and the amine corresponding to simple reduction of the double bond.The addition of the trichlorosilane requires no catalyst and the relative percentages of the products varies in a generally inverse fashion depending on the exact structure of the enamine.Evidence is given to support the assigned structure of the trichlorosilyl species and mechanisms are hypothesized to explain the formation of both products from a common intermediate.Steric rather than electronic factors are suggested as responsible for the observed balance between them.
- Snyder, Dudley C.
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p. 137 - 144
(2007/10/02)
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- Synthesis of Ketones by Cyclization of Cyano and Acetylenic Radicals: Use of δ-Hydroxy Nitriles and δ- or ε-Hydroxy Acetylenes
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The radical intermediates generated by deoxygenation of alcohols undergo intramolecular ring closure when suitably located triple bonds (CC or CN) are present; the reaction provides a new synthesis of bicyclic ketones from either monocyclic ketones or cyclic olefins.
- Clive, Derrick L. J.,Beaulieu, Pierre L.,Set, Lu
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p. 1313 - 1314
(2007/10/02)
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- The Chemistry of Aryllead(IV) Tricarboxylates. Reaction with Enamines
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The treatment of 1-morhpholinocyclopentene (1a) with p-methoxyphenyllead triacetate (2a) in chloroform provides a simple high-yielding route to 2-(4-methoxyphenyl)cyclopentanone (3a).This arylation reaction of enamines has been investigated with a variety of substrates and a number of aryllead triacetates.The reaction has been found to be very sensitive to steric effects and is thus a useful synthetic method in a relatively small number of cases.Acetoxylation is a major competing reaction with those enamines of cyclic ketones which give a low to moderate yield of arylated product.
- May, George L.,Pinhey, John T.
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p. 1859 - 1871
(2007/10/02)
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- BICYCLIC 1,2-OXAZINE N-OXIDES. DIFFERENT BEHAVIOUR IN RING FISSION BETWEEN SYSTEMS DERIVED FROM 5- AND 6-MEMBERED RING CYCLIC ENAMINES
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1,2-Oxazine N-oxides derived from aminocyclohexenes open into the corresponding nitroalkylated trisubstituted enamines, whereas those derived from aminocyclopentenes give stable tetrasubstituted enamines.Both open-chain systems are easily hydrolyzed to the corresponding χ-nitrocycloalkanones.
- Daneo, S.,Pitacco, G.,Risaliti, A.,Valentin, E.
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p. 1499 - 1504
(2007/10/02)
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- ENAMINE CHEMISTRY XX. SYNTHESIS OF FURAN DERIVATIVES BY REDUCTIVE CYCLISATION OF ENAMINES
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Enamines, I, prepared from cyclohexanones or cyclopentanones and pyrrolidine are alkylated with 2-bromoesters (ethyl 2-bromoethanoate, ethyl 2-bromopropanoate, methyl 2-bromopropanoate) to give new enamines, II, which after treatment with LiAlH4 undergo reductive cyclisation reactions giving the furan derivatives, III (7a-pyrrolidino-octahydrobenzofurans, 6a-pyrrolidino-hexahydrocyclopentafurans) in almost quantitative yields.The compounds III are hydrolyzed with hydrochloric acid to octahydrobenzofuran-7a-ols or hexahydrocyclopentafuran-6a-ols, IV.Elimination of pyrrolidine from III with oxalic acid in anhydrous dioxane yields condensed dihydrofurans, V.
- Carlsson, S.,El-Barbary, A. A.,Lawesson, S.-O.
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p. 643 - 650
(2007/10/02)
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