- A facile, one-pot synthesis of lacidipine using in situ generation of wittig intermediates
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An improved, one-pot process for the preparation of lacidipine (1) via an efficient in situ generation of Wittig intermediates is reported. Generation of ylide (4) by dehydrobromination of phosphonium salt (3) followed by in situ condensation of 4 with o-phthalaldehyde (5) to yield corresponding olefin (6) and its subsequent reaction with crotonate derivative (7) in the same pot furnished the drug substance 1 with an overall yield of about 51% over the reported yield of about 24% starting from the corresponding ylide. The present work overcomes the challenges associated with prior art processes such as chromatographic purifications, handling of unstable intermediates, and formation of byproducts as potential impurities. The interesting insights on the safety aspects of the process, drawn through calorimetric studies, rendered the successful implementation of the process at manufacturing facility.
- Prasada Raju,Ravindra, Vedantham,Mathad, Vijayavitthal T.,Dubey,Reddy, Padi Pratap
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- Regioselective organocatalyzed asymmetric bromolactonization of aryl acrylate-type carboxylic acids: a new approach towards enantioenriched 3-substituted isobenzofuranones
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The enantioselective synthesis of several 3-substituted isobenzofuranones has been developed through a new and flexible route. When combined with a catalytic amount of benzoic acid, quinidine thiocarbamate bifunctional catalysts have demonstrated their efficiency for the highly regioselective organocatalyzed asymmetric bromolactonization reaction of aryl acrylate-type carboxylic acids.
- Gelat, Fabien,Coffinet, Micha?l,Lebrun, Stéphane,Agbossou-Niedercorn, Francine,Michon, Christophe,Deniau, Eric
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- A solvent- And catalyst-free tandem reaction: Synthesis, and photophysical and biological applications of isoindoloquinazolinones
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An easy green synthetic approach for fused isoindoloquinazolinones has been developed under neat reaction (yields up to 91%) conditions. This new one-pot tandem methodology involves condensation of readily available anthranilamide with 3-(2-formylcycloalk
- Ali, Sk Asraf,Bera, Anirban,Ikbal, Mohammed,Manna, Susanta Kumar,Misra, Sandip,Saha, Amit,Samanta, Shubhankar
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- Enantioselective Stereodivergent Nucleophile-Dependent Isothiourea-Catalysed Domino Reactions
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α,β-Unsaturated acyl ammoniums generated from the reaction of α,β-unsaturated 2,4,6-trichlorophenol (TCP) esters bearing a pendent enone with an isothiourea organocatalyst are versatile intermediates in a range of enantioselective nucleophile-dependent domino processes to form complex products of diverse topology with excellent stereoselectivity. Use of either 1,3-dicarbonyls, acyl benzothiazoles, or acyl benzimidazoles as nucleophiles allows three distinct, diastereodivergent domino reaction pathways to be accessed to form various fused polycyclic cores containing multiple contiguous stereocentres.
- Matviitsuk, Anastassia,Taylor, James E.,Cordes, David B.,Slawin, Alexandra M. Z.,Smith, Andrew D.
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- Synthesis of Oxatricyclooctanes via Photoinduced Intramolecular Oxa-[4+2] Cycloaddition of Substituted o-Divinylbenzenes
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The photolysis of substituted o-divinylbenzenes promotes a one-step and metal-free conversion to oxatricycles at room temperature. Irradiation o-divinylbenzenes results in an pericyclic reaction to form cyclic o-quinodiemthane intermediates, which subsequently undergo intramolecular oxa-[4+2] cycloaddition to form oxacyclic derivatives.
- Liu, Qiang,Wang, Junlei,Li, Dazhi,Gao, Guo-Lin,Yang, Chao,Gao, Yuan,Xia, Wujiong
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p. 7856 - 7868
(2017/08/14)
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- CoIII-Carbene Radical Approach to Substituted 1H-Indenes
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A new strategy for the catalytic synthesis of substituted 1H-indenes via metalloradical activation of o-cinnamyl N-tosyl hydrazones is presented, taking advantage of the intrinsic reactivity of a CoIII carbene radical intermediate. The reaction uses readily available starting materials and is operationally simple, thus representing a practical method for the construction of functionalized 1H-indene derivatives. The cheap and easy to prepare low spin cobalt(II) complex [CoII(MeTAA)] (MeTAA = tetramethyltetraaza[14]annulene) proved to be the most active catalyst among those investigated, which demonstrates catalytic carbene radical reactivity for a nonporphyrin cobalt(II) complex, and for the first time catalytic activity of [CoII(MeTAA)] in general. The methodology has been successfully applied to a broad range of substrates, producing 1H-indenes in good to excellent yields. The metallo-radical catalyzed indene synthesis in this paper represents a unique example of a net (formal) intramolecular carbene insertion reaction into a vinylic C(sp2)-H bond, made possible by a controlled radical ring-closure process of the carbene radical intermediate involved. The mechanism was investigated computationally, and the results were confirmed by a series of supporting experimental reactions. Density functional theory calculations reveal a stepwise process involving activation of the diazo compound leading to formation of a CoIII-carbene radical, followed by radical ring-closure to produce an indanyl/benzyl radical intermediate. Subsequent indene product elimination involving a 1,2-hydrogen transfer step regenerates the catalyst. Trapping experiments using 2,2,6,6-tetra-methylpiperidine-1-oxyl (TEMPO) radical or dibenzoylperoxide (DBPO) confirm the involvement of cobalt(III) carbene radical intermediates. Electron paramagnetic resonance spectroscopic spin-trapping experiments using phenyl N-tert-butylnitrone (PBN) reveal the radical nature of the reaction.
- Das, Braja Gopal,Chirila, Andrei,Tromp, Moniek,Reek, Joost N. H.,De Bruin, Bas
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supporting information
p. 8968 - 8975
(2016/07/30)
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- Compound and its as L-type calcium channel blocker or/and application of acetylcholine esterase inhibitors
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Disclosed in this invention are compounds and the uses as L-type calcium channel blocker and/or acetylcholinesterase inhibitor thereof. The uses of said compounds in the manufactures of a medicament for the treatment of cardiovascular diseases, apoplexy or senile dementia are also disclosed in the present invention.
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Paragraph 0472-0473
(2016/10/07)
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- Rhodium(III)-catalyzed oxidative alkenylation of 1,3-dithiane-protected arenecarbaldehydes via regioselective C-H bond cleavage
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A Rh(III)-catalyzed direct alkenylation of 2-aryl-1,3-dithiane derivatives with alkenes has been developed. The 1,3-dithiane group can serve as an effective directing group for the exclusively monoselective alkenylation under mild oxidative conditions. Th
- Unoh, Yuto,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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p. 704 - 707
(2015/03/05)
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- NHC-catalyzed oxidative cyclization reaction for the synthesis of 3-substituted phthalides
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An efficient NHC-catalyzed domino oxidation/oxa-Michael addition reaction of 2-alkenylbenzaldehydes has been developed to afford 3-substituted phthalides bearing a C3-stereogenic center with a broad substrate scope and wide functional group tolerance. The preliminary results of the asymmetric process have been provided as well. the Partner Organisations 2014.
- Youn, So Won,Song, Hyoung Sub,Park, Jong Hyub
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supporting information
p. 2388 - 2393
(2014/04/03)
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- Tandem nucleophilic addition-intramolecular aza-michael reaction: Facile synthesis of chiral fluorinated isoindolines
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A highly stereoselective synthesis of fluorinated 1,3-disubstituted isoindolines is described. To this end, a tandem reaction consisting of a diastereoselective addition of fluorinated nucleophiles to Ellman's N-(tert-butanesulfinyl)imines followed by an
- Fustero, Santos,Moscardo, Javier,Sanchez-Rosello, Maria,Rodriguez, Elsa,Barrio, Pablo
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supporting information; experimental part
p. 5494 - 5497
(2011/02/23)
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- A tandem catalytic approach to methyleneindenes: Mechanistic insights into gem -dibromoolefin reactivity
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(Figure presented) The methylenindene scaffold can be prepared from readily available gem-dibromoolefins using an efficient palladium-catalyzed tandem intermolecular Suzuki/intramolecular Heck reaction. The reaction is highly modular and proceeds under mild conditions. The choice of ligand was found to be crucial to control the selectivity of the reaction. Isolation of intermediates under different conditions provides insight into the mechanism.
- Bryan, Christopher S.,Lautens, Mark
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supporting information; experimental part
p. 2754 - 2757
(2010/08/07)
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- An inexpensive and highly stable ligand 1,4-bis(2-hydroxy-3,5-di-tert-butylbenzyl)piperazine for Mizoroki-Heck and room temperature Suzuki-Miyaura cross-coupling reactions
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A bulky, inexpensive and simple bidentate ligand 1,4-bis(2-hydroxy-3,5-di-tert-butylbenzyl)piperazine (1) has been synthesized and characterized. The palladium catalyst was formed by combination of 1 with [Cl2Pd(COD)] in a ratio of 1:1, tested in the Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions. Coupling of a variety of aryl bromides with phenylboronic acid using methanol as solvent at room temperature, or at 60 °C, gave generally high yields of coupled products. Coupling of aryl chlorides with organoboron reagent at 110 °C in DMF afforded good yields of biaryls under aerobic conditions. This non-phosphorus, air and moisture stable catalyst also displays good activity for Mizoroki-Heck coupling reaction in methanol at 60 °C with various aryl chlorides and bromides.
- Mohanty, Sasmita,Suresh,Balakrishna, Maravanji S.,Mague, Joel. T.
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p. 240 - 247
(2008/09/16)
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- PROCESS FOR PREPARING LACIDIPINE
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A process for preparing lacidipine, comprising reacting a t-butoxy carbonyl methyl aryl phosphonium halide with o-phthalaldehyde, and further reacting a product comprising (E)-3-(2-formylphenyl)-2-propenoic acid, 1,1-dimethyl ethyl ester, without isolation, with ethyl-3-amino crotonate.
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Page/Page column 6-7
(2010/11/25)
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