- A new nitrogen-to-oxygen phosphoryl migration
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The reaction of diethyl N-acetyl-N-methylphosphoramidate 1 with aldehyde in the presence of LDA at -70°C results in the formation of the unstable oxyanion 6 which undergoes intramolecular rearrangement involving migration of a phosphoryl group from nitrogen to oxygen affording an amide anion 8. Subsequent proton transfer in 8 followed by elimination of phosphate anion provides the respective α,β-unsaturated N-methylcarboxamide 4. The formation of considerable amounts of diethyl N-methylphosphoramidate 5 is also always observed.
- Koziara,Zwierzak
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Read Online
- Organocatalytic Trans Semireduction of Primary and Secondary Propiolamides: Substrate Scope and Mechanistic Studies
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We report a chemoselective, phosphine-catalyzed semireduction of primary and secondary propiolamides. In the presence of stoichiometric pinacolborane and catalytic n-tributylphosphine, a variety of propiolamides were successfully converted to the corresponding acrylamides in excellent yield with (E)-stereoselectivity. The reaction condition is tolerant of various functional groups including alkene, alkyne, ketone, or ester. Deuterium labeling studies established that the hydride from activated pinacolborane is added to the α-carbon and the proton on the amide nitrogen is abstracted by the ?-carbon to furnish the (E)-acrylamides. DFT calculations revealed a clear energetic driving force for the (E)- over the (Z)-isomer. (Figure presented.).
- Grams, R. Justin,Lawal, Monsurat M.,Szwetkowski, Connor,Foster, Daniel,Rosenblum, Carol Ann,Slebodnick, Carla,Welborn, Valerie Vaissier,Santos, Webster L.
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supporting information
p. 172 - 178
(2021/10/14)
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- Manganese Catalyzed Enantioselective Epoxidation of α,β-Unsaturated Amides with H2O2
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Herewith, we report the enantioselective epoxidation of electron-deficient cis- and trans-α,β-unsaturated amides with the environmentally benign oxidant H2O2. The catalysts - manganese complexes with bis-amino-bis-pyridine and structurally related ligands - exhibit reasonably high efficiency (up to 100 TON) and excellent chemo- and enantioselectivity (up to 100% and 99% ee, respectively). Crucially, the cis-enamides epoxidation enantioselectivity and yield are dramatically enhanced by the presence of NH-moiety, which effect can be explained by the hydrogen bonding interaction between the cis-enamide substrate and the manganese based oxygen transferring species. (Figure presented.).
- Ottenbacher, Roman V.,Kurganskiy, Vladimir I.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
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supporting information
p. 2778 - 2782
(2021/04/29)
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- Dealkoxylation ofN-alkoxyamides without an external reductant driven by Pd/Al cooperative catalysis
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Lewis acid-assisted palladium-catalysed dealkoxylation ofN-alkoxyamides has been developed. This reaction proceeded smoothly with a range ofN-alkoxyamides in the absence of an external reductant, thereby establishing a convenient and reductant-free protocol. In addition, a gram-scale reaction could be achieved. Preliminary mechanistic investigations indicated that β-hydrogen elimination from a palladium alkoxide intermediate generated an intramolecular hydride source.
- Suzuki, Hirotsugu,Shiomi, Takahiro,Yoneoka, Kenji,Matsuda, Takanori
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supporting information
p. 7545 - 7548
(2020/10/15)
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- Catalytic, transition-metal-free semireduction of propiolamide derivatives: Scope and mechanistic investigation
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We report a transition-metal-free trans-selective semireduction of alkynes with pinacolborane and catalytic potassium tert-butoxide. A variety of 3-substituted primary and secondary propiolamides, including an analog of FK866, a potent nicotinamide mononucleotide adenyltransferase (NMNAT) inhibitor, are reduced to the corresponding (E)-3-substituted acrylamide derivatives in up to 99% yield with >99:1 E/Z selectivity. Mechanistic studies suggest that an activated Lewis acid-base complex transfers a hydride to the α-carbon followed by rapid protonation in a trans fashion.
- Grams, R. Justin,Garcia, Christopher J.,Szwetkowski, Connor,Santos, Webster L.
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supporting information
p. 7013 - 7018
(2020/09/12)
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- Copper(I)-Catalyzed Asymmetric 1,4-Conjugate Hydrophosphination of α,β-Unsaturated Amides
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A catalytic asymmetric conjugate hydrophosphination of α,β-unsaturated amides is accomplished by virtue of the strong nucleophilicity of copper(I)-PPh2 species, which provides an array of chiral phosphines bearing an amide moiety in high to excellent yields with excellent enantioselectivity. Furthermore, the dynamic kinetic resolution of unsymmetrical diarylphosphines (HPAr1Ar2) is successfully carried out through the copper(I)-catalyzed conjugate addition to α,β-unsaturated amides, which affords P-chiral phosphines with good-to-high diastereoselectivity and high enantioselectivity. 1H NMR studies show that the precoordination of HPPh2 to copper(I)-bisphosphine complex is critical for the efficient deprotonation by Barton's Base. Moreover, the relative stability of the copper(I)-(R,RP)-TANIAPHOS complex in the presence of excessive HPPh2, confirmed by 31P NMR studies, is pivotal for the high asymmetric induction, as the ligand exchange between bisphosphine and HPPh2 would significantly reduce the enantioselectivity. At last, a double catalytic asymmetric conjugate hydrophosphination furnishes the corresponding product in high yield with high diastereoselectivity and excellent enantioselectivity, which is transformed to a chiral pincer palladium complex in moderate yield. This chiral palladium complex is demonstrated as an excellent catalyst in the asymmetric conjugate hydrophosphination of chalcone.
- Li, Yan-Bo,Tian, Hu,Yin, Liang
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supporting information
p. 20098 - 20106
(2021/01/01)
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- Chemoselective Synthesis of Aryl Ketones from Amides and Grignard Reagents via C(O)-N Bond Cleavage under Catalyst-Free Conditions
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Conversion of a wide range of N-Boc amides to aryl ketones was achieved with Grignard reagents via chemoselective C(O)-N bond cleavage. The reactions proceeded under catalyst-free conditions with different aryl, alkyl, and alkynyl Grignard reagents. α-Ketoamide was successfully converted to aryl diketones, while α,β-unsaturated amide underwent 1,4-addition followed by C(O)-N bond cleavage to provide diaryl propiophenones. N-Boc amides displayed higher reactivity than Weinreb amides with Grignard reagents. A broad substrate scope, excellent yields, and quick conversion are important features of this methodology.
- Sureshbabu, Popuri,Azeez, Sadaf,Muniyappan, Nalluchamy,Sabiah, Shahulhameed,Kandasamy, Jeyakumar
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p. 11823 - 11838
(2019/10/02)
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- Bioactivity and structure–activity relationship of cinnamic acid derivatives and its heteroaromatic ring analogues as potential high-efficient acaricides against Psoroptes cuniculi
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A series of cinnamic acid derivatives and its heteroaromatic ring analogues were synthesized and evaluated for acaricidal activity in vitro against Psoroptes cuniculi, a mange mite. Among them, eight compounds showed the higher activity with median lethal concentrations (LC50) of 0.36–1.07 mM (60.4–192.1 μg/mL) and great potential for the development of novel acaricidal agent. Compound 40 showed both the lowest LC50 value of 0.36 mM (60.4 μg/mL) and the smallest median lethal time (LT50) of 2.6 h at 4.5 mM, comparable with ivermectin [LC50 = 0.28 mM (247.4 μg/mL), LT50 = 8.9 h], an acaricidal drug standard. SAR analysis showed that the carbonyl group is crucial for the activity. The type and chain length of the alkoxy in the ester moiety and the steric hindrance near the ester group significantly influence the activity. The esters were more active than the corresponding thiol esters, amides, ketones or acids. Replacement of the phenyl group of cinnamic esters with α-pyridyl or α-furanyl significantly increase the activity. Thus, a series of cinnamic esters and its heteroaromatic ring analogues with excellent acaricidal activity emerged.
- Chen, Dong-Dong,Zhang, Bing-Yu,Liu, Xiu-Xiu,Li, Xing-Qiang,Yang, Xin-Juan,Zhou, Le
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p. 1149 - 1153
(2018/03/05)
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- Tandem superelectrophilic hydroarylation of CC bond and carbonyl reduction in cinnamides: Synthetic rout to 3,3-diarylpropylamines, valuable pharmaceuticals
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Cinnamides ArCHCHCONRR′ in reactions with arenes Ar′H under the action of Bronsted (TfOH, FSO3H) or Lewis (AlBr3) superacids at rt for 1-2 h give CC bond hydroarylation products ArAr′CHCH2CONRR′ in yields of 63-98%. Reduction (LiAlH4/Et2O) of carbonyl group in the latter results in the formation of 3,3-diarylpropylamines ArAr′CHCH2CH2NRR′, valuable drugs. The reaction intermediates, superelectrophilic dications ArC+H-CH2C(OH+)NRR′, have been characterized by DFT calculations in terms of global electrophilicity index, natural charges, and atomic orbitals contributions.
- Zakusilo, Dmitry N.,Ryabukhin, Dmitry S.,Boyarskaya, Irina A.,Yuzikhin, Oleg S.,Vasilyev, Aleksander V.
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p. 102 - 108
(2015/02/02)
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- Reductive N-O cleavage of Weinreb amides by sodium in alumina and silica gels: synthetic and mechanistic studies
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The use of sodium in alumina and silica gels for the reductive cleavage of the N-O bond of N-methoxy-N-methylamides, commonly referred to as Weinreb amides, has been investigated. This method reduces a diverse set of Weinreb amides with different function
- Jackson, James E.,O'Brien, Brittany N.,Kedzior, Sonya K.,Fryz, Gage R.,Jalloh, Fatmata S.,Banisafar, Arash,Caldwell, Michael A.,Braun, Max B.,Dunyak, Bryan M.,Dye, James L.
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supporting information
p. 6227 - 6230
(2015/10/20)
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- Metal-free tandem oxidative aryl migration and C-C bond cleavage: Synthesis of α-ketoamides and esters from acrylic derivatives
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A novel tandem metal-free oxidative aryl migration/C-C bond-cleavage reaction, mediated by hypervalent iodine reagent, has been discovered. The presented transformation provided straightforward access to important α-ketoamide and α-ketoester derivatives from readily available acrylic derivatives via a concerted process of 1,2-aryl shift concomitant with C-C bond cleavage.
- Liu, Le,Du, Liang,Zhang-Negrerie, Daisy,Du, Yunfei,Zhao, Kang
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supporting information
p. 5772 - 5775
(2015/02/19)
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- Copper-catalyzed N-methylation of amides and O-methylation of carboxylic acids by using peroxides as the methylating reagents
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The copper-catalyzed N-methylation of amides and O-methylation of carboxylic acids by using peroxides as the methylating reagent are described. Various amides and carboxylic acids were methylated affording N-substituted amides and esters. Tentative mechanistic studies suggest that this reaction is likely to involve a radical process.
- Xia, Qinqin,Liu, Xiaolong,Zhang, Yuejiao,Chen, Chao,Chen, Wanzhi
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supporting information
p. 3326 - 3329
(2013/07/26)
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- The triflic acid-mediated cyclisation of N-benzyl-cinnamamides
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N-Benzyl-cinnamamides cyclise with triflic acid to form 5-aryl-benzazepinones and/or cinnamamides.
- King, Frank D.,Caddick, Stephen
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supporting information
p. 487 - 491
(2013/07/27)
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- A novel organic electron donor derived from N-methylisatin
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We report the reactivity of an electron donor derived from N-methylisatin on reduction by sodium amalgam. Transfer of a clear supernatant solution to iodoarenes affords the products of two-electron reduction. Reductions of sulfones, activated arenesulfonamides, and Weinreb amides are also reported.
- Sword, Ryan,O'Sullivan, Steven,Murphy, John A.
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p. 314 - 322
(2013/05/08)
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- Stereoselective olefination and regiospecific vicinal difunctionalization of imines with α-(benzothiazol-2-ylsulfonyl) carbonyl compounds
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Depending on their structures, imines are able to undergo either olefination or vicinal difunctionalization with various α-(benzothiazol-2- ylsulfonyl) carbonyl compounds in the absence of external bases. The olefination reaction of aromatic imines with α-(benzothiazol-2-ylsulfonyl) carbonyl compounds proceeds smoothly in tetrahydrofuran at 70 °C to give structurally diverse α,β-unsaturated esters, amides, and ketones in good to excellent yields and with extremely high (E) selectivity. In contrast, the carbon-nitrogen double bonds of cyclic imines and the carbon-carbon double bonds of α,β-unsaturated imines are subjected to regiospecific vicinal difunctionalization with α-(benzothiazol-2-ylsulfonyl) carbonyl compounds under the same reaction conditions to give a variety of benzothiazole derivatives in good to excellent yields. It is noteworthy that the benzothiazole moiety is present in a number of antitumor agents and bioluminescent molecules. In addition, plausible reaction pathways have been proposed to account for these transformations, and these are substantially supported by ESI-MS analysis of the reaction mixtures.
- Shao, You-Dong,Wu, Xue-Song,Tian, Shi-Kai
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supporting information; experimental part
p. 1590 - 1596
(2012/05/07)
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- Ruthenium-catalyzed reduction of N-alkoxy- and N-hydroxyamides
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A ruthenium-catalyzed reduction of N-alkoxy- and N-hydroxyamides was found to afford corresponding amides in good to high yields. A simple RuCl 3/Zn-Cu/alcohol system, without the addition of any other ligands, exhibited a high catalytic activity, and therefore the present reaction does not require a stoichiometric amount of metals or metal complexes as reductants. When β-substituted-α,β-unsaturated N-methoxyamides were employed as substrates, concurrent hydrogenation of the olefin moiety proceeded slowly with deprotection of the methoxy group. In the reduction of N-hydroxyamides, the alcoholic solvent was found to function as a hydrogen donor.
- Fukuzawa, Hiroko,Ura, Yasuyuki,Kataoka, Yasutaka
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p. 3643 - 3648
(2011/12/02)
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- Ruthenium-catalyzed oxidative synthesis of 2-pyridones through C-H/N-H bond functionalizations
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An inexpensive ruthenium catalyst enabled oxidative annulations of alkynes by acrylamides with ample scope, which allowed for the preparation of 2-pyridones employing various electron-rich and electron-deficient acrylamides as well as (di)aryl- and (di)alkyl-substituted alkynes.
- Ackermann, Lutz,Lygin, Alexander V.,Hofmann, Nora
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supporting information; experimental part
p. 3278 - 3281
(2011/08/06)
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- Boronic acid catalysis for mild and selective [3+2] dipolar cycloadditions to unsaturated carboxylic acids
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Herein, the concept of boronic acid catalysis (BAC) for the activation of unsaturated carboxylic acids is applied in several classic dipolar [3 + 2] cycloadditions involving azides, nitrile oxides, and nitrones as partners. These cycloadditions can be used to produce pharmaceutically interesting, small heterocyclic products, such as triazoles, isoxazoles, and isoxazolidines. These cycloadducts are formed directly and include a free carboxylic acid functionality that can be employed for fur-ther transformations, thereby avoiding prior masking or functionalization. In all cases, BAC provides faster reactions, under milder conditions, with much improved product yields and regioselectivities. In some instances, such as triazole formation from the reaction of azides with 2-alkynoic acids, catalysis with ort/io- nitrophenylboronic acid circumvents the undesirable product decarboxylation observed when using thermal activation. By using NMR spectroscopic studies, the boronic acid catalyst was shown to provide activation by a LUMO-lowering effect in the unsaturated carboxylic acid, likely via a monoacylated hemiboronic ester intermediate.
- Zheng, Hongchao,McDonald, Robert,Hall, Dennis G.
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experimental part
p. 5454 - 5460
(2010/09/15)
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- Metal-free reductive cleavage of N-O bonds in weinreb amides by an organic neutral super-electron donor
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The scope of neutral organic super-electron donors as reducing agents has been extended to include the reductive cleavage of N-O bonds in Weinreb amides. This methodology proved to be applicable to a large array of substrates to afford their reduced counterparts in good to excellent yields. The variation in reactivity within the set of tested amides is rationalised. Georg Thieme Verlag Stuttgart.
- Cutulic, Sylvain P. Y.,Murphy, John A.,Farwaha, Hardeep,Zhou, Sheng-Ze,Chrystal, Ewan
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experimental part
p. 2132 - 2136
(2009/04/08)
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- Mild zinc-promoted Horner-Wadsworth-Emmons reactions of diprotic phosphonate reagents
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We report the development of a mild protocol for the Horner-Wadsworth- Emmons reaction of diprotic phosphonates that makes use of a zinc triflate promoter in the presence of mild ter-tiary amine bases to produce α,β-unsaturated carboxylic acids and amides. Georg Thieme Verlag Stuttgart.
- Schauer, Douglas J.,Helquist, Paul
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p. 3654 - 3660
(2008/03/13)
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- A novel method for the synthesis of α,β-unsaturated amides mediated by Samarium diiodide
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Promoted by Samarium diiodide (SmI2), α,β-unsaturated amides were formed from nitrogenanions (formed in situ by the reduction of nitro compounds) and αβ-unsaturated esters. This reaction contrasts with the conjugate addition between amines and α,β-unsaturated esters promoted by samarium triiodide (SmI3) and provides an alternative attractive way to obtain α,β-unsaturated amides using SmI 2.
- Zhu, Chun-Lan,Wang, Xia-Xia
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p. 953 - 955
(2007/10/03)
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- Efficient Synthesis of Chiral α- and β-Hydroxy Amides: Application to the Synthesis of (R)-Fluoxetine
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Four flavors for epoxide openings: The regioselective openings of epoxy amides obtained by asymmetric epoxidation yields all types of aryl- and alkyl-substituted hydroxy amides sometimes counter to the reactivity of the α- and β-positions.
- Kakei, Hiroyuki,Nemoto, Tetsuhiro,Ohshima, Takashi,Shibasaki, Masakatsu
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p. 317 - 320
(2007/10/03)
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- Synthesis and reactions of 2-substituted ethyl N-alkylmalonylhydroxamic acids
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Alkylation of O-silylated N-alkylmalonylhydroxamic acids provides a method for the synthesis of 2-substituted N-alkylmalonyl hydroxamic acids. The substituent at C-2 does not materially change the chemistry of the α-lactam intermediates produced from them. They can be converted to unsymmetric ureas and hydantoins in high yields. The addition of unsaturated substituents at C-2 is used to produce cyclic ureas containing medium rings via RCM reactions.
- Hoffman, Robert V.,Madan, Sachin
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p. 4876 - 4885
(2007/10/03)
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- Novel delta dicarbonyl compounds and methods for using same
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Amidomethyl esters, carbonylmercaptomethyl esters, keto-containing esters, amidomethyl thioesters, amidomethyl amides, and methylene dithioesters are disclosed. The novel compounds have two carbonyl groups connected by a linking moiety having an oxygen, s
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- Catalytic asymmetric epoxidation of α,β-unsaturated amides: Efficient synthesis of β-aryl α-hydroxy amides using a one-pot tandem catalytic asymmetric epoxidation - Pd-catalyzed epoxide opening process
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The catalytic asymmetric epoxidation of α,β-unsaturated amides using Sm-BINOL-Ph3As=O complex was succeeded. Using 5-10 mol % of the asymmetric catalyst, a variety of amides were epoxidized efficiently, yielding the corresponding α,β-epoxy amides in up to 99% yield and in more than 99% ee. Moreover, the novel one-pot tandem process, one-pot tandem catalytic asymmetric epoxidation-Pd-catalyzed epoxide opening process, was developed. This method was successfully utilized for the efficient synthesis of β-aryl α-hydroxy amides, including β-aryllactyl-leucine methyl esters. Interestingly, it was found that beneficial modifications on the Pd catalyst were achieved by the constituents of the first epoxidation, producing a more suitable catalyst for the Pd-catalyzed epoxide opening reaction in terms of chemoselectivity. Copyright
- Nemoto, Tetsuhiro,Kakei, Hiroyuki,Gnanadesikan, Vijay,Tosaki, Shin-Ya,Ohshima, Takashi,Shibasaki, Masakatsu
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p. 14544 - 14545
(2007/10/03)
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- The Influence of Inter- and Intramolecular Hydrogen Bonding upon the Structure and Photochemistry of 3-(2-Pyridyl)propenamides
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The molecular structures and photochemical behavior of (E)- and (Z)-N-methyl-3-(2-pyridyl)propenamide have been investigated in the solid state and in solution.While the molecular conformation of the thermodynamically more stable E isomer is independent o
- Lewis, Frederick D.,Yoon, Beth A.
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p. 2537 - 2545
(2007/10/02)
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- Synthesis of the Alkaloid Homaline in (+/-) and Natural (S,S)-(-) Forms, using Amination and Transamidative Ring Expansion in Liquid Ammonia
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Synthesis of the alkaloid homaline in (+/-) and natural (S,S)-(-) forms is reported.Linking of 2-azacyclooctanone units either directly or successively using 1,4-dihalogenobutanes or 1,4-dihalogenobut-2-ynes is examined. (+/-)-5-Methyl-4-phenyl-1,5-diazacyclooctan-2-one is first made by a 2,2'-dithiodipyridine/triphenylphosphine-mediated cyclisation, and then by amination and transamidative ring expansion from N-(3-chloropropyl)-4-phenylazetidin-2-one in liquid ammonia, followed by N-methylation.Coupling through a 1,4-dihalogenobutane of either the N-methylated azalactam, or the unmethylated azalactam followed by methylation, gave homaline in (+/-) and meso forms. (R)-(-)-Phenylglycine was converted via (S)-β-phenyl-β-alanine into an (S)-β-lactam which was then alkylated with 1-bromo-3-chloropropane, and aminated and ring expanded in liquid ammonia.Coupling of the homochiral azalactam (2 mol) so formed with 1,4-dibromobutane, followed by N-methylation, gave (S,S)-(-)-homaline identical with the natural material.
- Crombie, Leslie,Haigh, David,Jones, Raymond C. F.,Mat-Zin, Ab. Rasid
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p. 2047 - 2054
(2007/10/02)
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- An Unusual Ring-Cleavage of 2,4-Di-N-methylcarbamoylcyclohexanones into Glutaconimide and Cinnamamides
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3-Aryl-5-hydroxy-5-methyl-2,4-di-N-methylcarbamoylcyclohexanones (1a-h) under acidic and basic conditions underwent ring-cleavage to give 1,4-dimethylglutaconimide (3) and substituted N-methylcinnamamides (4a-h).The probable mechanism for the formation of
- Sadanandam, Yennu S.,Leelavathi, Panaganti,Ansari, Imtiaz A.
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p. 1147 - 1158
(2007/10/02)
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- Photophysical and photochemical behavior of intramolecular-styrene-amine exciplexes
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The photophysical and photochemical behavior of a series of secondary and tertiary ω-(β-styryl)aminoalkanes with one to five methylenes separating the styryl and amino groups has been investigated and compared to the intermolecular reactions of 1-phenylpropene with secondary and tertiary amines. The tertiary styrylamines form fluorescent intramolecular exciplexes, but fail to undergo intramolecular addition reactions. Both the rate constant for exciplex formation and the stability of the exciplex are dependent upon the length of the polymethylene chain connecting the chromophores. The failure of the tertiary amine exciplexes to undergo intramolecular addition is attributed to an unfavorable exciplex geometry for α-C-H transfer to the styrene double bond. While the secondary styrylamines do not form fluorescent exciplexes, the dependence of the styrene singlet lifetime upon the polymethylene chain length is similar to that for the tertiary styrylamines. Intramolecular N-H addition to the styrene double bond results in the formation of two regioisomeric (α-phenyl and α-benzyl) cyclic amines of different ring size. The regioisomer of larger ring size is favored except in the case in which four methylenes separate the chromophores. The effects of polymethylene chain length, solvent polarity, temperature, and the bulk of the N-alkyl group upon product yields and ratios are discussed in terms of a mechanism involving singlet exciplex and biradical intermediates.
- Lewis, Frederick D.,Dasharatha Reddy,Schneider, Siegfried,Ga, Michael
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p. 3498 - 3506
(2007/10/02)
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- Structure and Photoisomerization of (E)- and (Z)-Cinnamamides and Their Lewis Acid Complexes
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The spectroscopic properties and photoisomerization reactions of several (E)- and (Z)-cinnamamides have been investigated in the absence and presence of the strong Lewis acid BF3.The (E)-cinnamamides are essentially planar and exist predominantly in the enone s-cis conformation, except in the case of the α-methyl tertiary amide which adopts the s-trans conformation in order to minimize nonbonded repulsion.The (Z)-cinnamamides exist predominantly in the highly nonplanar s-trans conformation.This unusual conformational preference is attributed to intramolecular charge transfer from the aromatic to amide functionality.Photoisomerization efficiencies are dependent upon N-alkylation, aromatic substitution, α-alkylation, and excitation wavelength.These effects are attributed to the existence of two lowest energy ?,?* singlet states (one reactive and one nonreactive) whose relative energies are dependent upon substitution.The cinnamamides form 1:1 complexes with BF3 with equilibrium constants >103.Complexation alters both the electronic structure and photochemical behavior of the cinnamamides.Quantitative E -> Z isomerization has been observed for the BF3 complexes of two tertiary amides.
- Lewis, Frederick D.,Elbert, Jeffrey E.,Upthagrove, Alana L.,Hale, Paul D.
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p. 553 - 561
(2007/10/02)
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- REACTION OF α, β-UNSATURATED ACYL ISOTHIOCYANATES WITH SALTS OF DITHIOCARBAMIC ACIDS
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The reaction of unsaturated isothiocyanates with the sodium and calcium salts of N-alkyl- and N,N-dialkyldithiocarbamic acids was studied.Depending on the structure of the dithiocarbamate, the reaction products are thiazines or acyl dithiocarbamates.For the salts of methyldithiocarbamic acid the effect of the concentration and the nature of the metal on the relative yields of 6-phenyl-3-methylpropiorhodanine and 6-phenylpropiorhodanine was studied.A method is proposed for the synthesis of 3-substituted propiorhodanines.
- Krus, K.,Masias, A.,Beletskaya, I. P.
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p. 1421 - 1425
(2007/10/02)
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- CONJUGATE ADDITION OF ORGANOCOPPER REAGENTS TO N-TOSYLATED α, β-UNSATURATED AMIDES
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N-Tosylated α, β-unsaturated amides and lactams undergo facile conjugate addition with R2CuLi or RMgX/CuI (cat.).Stereoselective synthesis of trans-β,γ-dialkyl-γ-lactams can be achieved by this procedure.The resulting N-tosylamide moiety is further transformed to alcohol and several carbonyl compounds by way of reduction or nucleophillic displacement.
- Nagashima, Hideo,Ozaki, Nobuyasu,Washiyama, Masayoshi,Itoh, Kenji
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p. 657 - 660
(2007/10/02)
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- The Chemistry of Nitrilium Salts. Part 2. The Preparation of Nitrilium Trifluoromethanesulphonate Salts and Their Reactions with Some Oxygen and Sulphur Nucleophiles
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The syntheses of the nitrilium salts NMe>+3SCF3 i, PhCH2, Ph, CH2=CHCH2, NC(CH2)3, and CH2=CH> by reaction of MeO3SCF3 with the corresponding nitriles are described. the similar reaction between (E)-PhCH=CHCN and MeO3SCF3 gives a mixture of NMe>+SCF3 and the s-triazinium salt 3C3N3H>+3SCF3, which hydrolyzes to give (E)-PhCH=CHCONHMe and the triazine.The compound CF3SO3(CH2)4CN, prepared from I(CH2)4CN and AgO3SCF3, does not form a cyclic nitrilium salt, but slowly dimerizes at room temperature to N(CH2)4CN>+3SCF3.Both I(CH2)4CN and CF3SO3(CH2)4CN can be converted into the salt NMe>+3SCF3, but this does not form a dinitrilium salt on reaction with acetonitrile.On heating benzophenone oxime with CF3SO3H Beckmann rearrangement products are obtained, but conversion of +SCF3 into the nitrilium salt NPh>*3SCF3 ocuurs in only low yield even after 8 h at 130 deg C under high vacuum.The nitrilium salts with R = Ph, Me, Pri, and PhCH2 undergo rapid exothermic reaction with phenol, thiophenol, alcohols, and thiols to give the corresponding imidate and thioimidate salts in high yields. 4,4-Dimethy-2-phenyl-1,3-oxazoline is obtained in 74percent yield on heating NMe>+*3SCF3 with H2NCMe2CH2OH, and both this and 2,4,4-trimethyloxazoline react with MeO3SCF3 to give almoust quantitative yields of the corresponding N-methyloxazolinium salts, which can be reduced to the oxazolidines with NaBH4.N-Methyloxazolinium salts have also been obtained from the reactions of nitrilium salts (R = Ph or Me) with ethylene oxide.
- Booth, Brian L.,Jibodu, Kehinde O.,Proenca, M. Fernanda J. R. P.
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p. 1067 - 1073
(2007/10/02)
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- AN ALTERNATIVE PROCEDURE FOR THE ALUMINUM-MEDIATED CONVERSION OF ESTERS TO AMIDES
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A convenient method has been developed for directly converting esters to amides using reagents derived from the reaction of trimethylaluminum with ammonium chloride, methylamine hydrochloride or dimethylamine hydrochloride.
- Levin, Jeremy I.,Turos, Edward,Weinreb, Steven M.
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p. 989 - 994
(2007/10/02)
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- Phosphite-Mediated in Situ Carboxyvinylation: A New General Acrylic Acid Synthesis
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Sequential treatment of a 2-halo carboxylic acid with a dialkyl phosphite and an aldehyde or ketone in the presence of 3 equiv of sodium hydride in glyme constitutes a new general acrylic acid synthesis superior to conventional methods.An alkoxide-in-alcohol variant may be used with bromo- or chloroacetic acid and aryl aldehydes to produce cinnamic acids conveniently.The scope and other features of the synthesis are discussed.
- Brittelli, David R.
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p. 2514 - 2520
(2007/10/02)
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- The Synthesis and Some Reactions of N-Methylnitrilium Trifluoromethanesulphonate Salts
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N-Methylnitrilium trifluoromethanesulphonate (triflate) salts, prepared from nitriles and methyl triflate, have been shown to be useful reagents for the synthesis of aromatic ketimines and ketones, amidinium, imidate, and thioimidate salts, benzimidazoles, benzoxazoles, benzothiazoles, quinazolinones, and 1,2,4-triazolinium salts.
- Booth, Brian L.,Jibodu, Kehinde O.,Proenca, M. Fernanda
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p. 1151 - 1153
(2007/10/02)
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