- Rhodium-catalyzed arylative cyclization for the enantioselective synthesis of (trifluoromethyl)cyclobutanols
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A rhodium-catalyzed cyclization of 1-(trifluoro-methyl)-4-alkyn-1-ones with arylboronic acids is described to yield a novel class of small rings: (trifluoromethyl)cyclobutanols bearing an exocyclic double bond. The use of a rhodium/chiral diene complex allowed the reaction to proceed under mild conditions, often with high enantioselectivity. An X-ray crystal structure was obtained confirming the formation of the four-membered ring products.
- Johnson, Thomas,Choo, Ken-Loon,Lautens, Mark
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- Cobalt-Catalyzed Alkenylzincation of Unfunctionalized Alkynes
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While transition metal catalyzed addition reactions of arylmetal reagents to unfunctionalized alkynes have been extensively developed in the last decade, analogous reactions using alkenylmetal reagents remain rare regardless of their potential utility for the synthesis of unsymmetrical 1,3-dienes. Reported herein is the development of a cobalt/diphosphine catalyst which promotes efficient and stereoselective addition of alkenylzinc reagents to unfunctionalized internal alkynes. The resulting dienylzinc species serve as versatile intermediates for further synthetic transformations.
- Wu, Junliang,Yoshikai, Naohiko
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supporting information
p. 336 - 340
(2016/01/25)
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- Synthesis of bicyclic N,N-enaminals by cyclization of alk-4-ynals with aliphatic diamines in DMSO upon treatment with KOH
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A cyclization of alk-4-ynals with aliphatic diamines in DMSO upon treatment with KOH was found to lead to bicyclic N,N-enaminals. The studies of this reaction showed that 1,3-diaminopropane and N-methyl-1,3-diaminopropane gave (E)-6-(arylmethylidene)octahydropyrrolo[1,2-a]pyrimidines in 45 - 78% yields, whereas 1,2-diaminoethane gave 5-(arylmethylidene)hexahydropyrrolo[1,2-a] imidazoles as mixtures of E- and Z-isomers in up to 75% total yield. The mechanism of these new cascade cyclization reactions includes formation of the equilibrium mixtures of imines and cyclic aminals with subsequent intramolecular hydroamination of the triple bond having considerable ionic character.
- Gvozdev,Shavrin,Nefedov
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p. 2430 - 2437
(2014/11/08)
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- Synthesis of 6-(arylmethylidene)octahydropyrrolo[1,2-a]pyrimidines and 5-(arylmethylidene)hexahydropyrrolo[1,2-a]imidazoles by the interaction of alk-4-ynals with a,?-diaminoalkanes in DMSO in the presence of KOH
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Cyclization of alk-4-ynals with a,?-diaminoalkanes in DMSO under the action of KOH affords bicyclic N,N-enaminals - 6-(aryl- methylidene)octahydro[1,2-a] pyrimidines and 5-(arylmethylidene)hexahydro[1,2-a]imidazoles.
- Shavrin, Konstantin N.,Gvozdev, Valentin D.,Nefedov, Oleg M.
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p. 140 - 141
(2013/07/26)
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- Synthesis of 5-methylidenehexahydropyrrolo[l,2-a]imidazoles and 6-methylideneoctahydropyrrolo[l,2-a]pyrimidines by the reaction of 1-alkynyl-1-chlorocyclopropanes with lithium derivatives of 1,2- and 1,3-diaminoalkanes
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A reaction of 1-alkynyl-1-chlorocyclopropanes with excess of lithium derivative of 1,2-diaminoethane leads to 5-methylidenehexahydropyrrolo[l,2-a] imidazoles in 35-72% yields, whereas analogous reaction with lithium derivative of 1,3-diaminopropane gives 6-methyl-ideneoctahydropyrrolo[l,2-a]pyrimidine in up to 50% yield. A mechanism of these unusual multi-step processes includes dehydrochlorination of 1-alkynyl-1-chlorocyclopropanes to form conjugated alkynylcyclopropenes capable of addition of monoalkylamide ions at the double bond, leading to the corresponding secondary cyclopropylamines; the latter under the reaction conditions isomerize to the linear imines, which further undergo a cascade cyclization with sequential involvement of the C=N and C≡C bonds.
- Shavrin,Gvozdev,Nefedov
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scheme or table
p. 1451 - 1458
(2011/04/16)
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- Catalytic one-pot synthesis of [5.5.5.6]fenestrane systems via a dicobalt octacarbonyl-catalyzed tandem cycloaddition of dienediynes
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Catalytic one-pot synthesis of fenestrane derivatives from dienediynes was developed: fenestranes were synthesized in high yields by a dicobalt octacarbonyl-catalyzed tandem cycloaddition of dienediynes.
- Kim, Do Han,Son, Seung Uk,Chung, Young Keun,Lee, Sueg-Geun
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- Synthetic studies towards ML-3000: A concise synthesis of this non- steroidal anti-inflammatory drug
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ML-3000 was obtained from 1-chloro-3-phenyl-2-propyne in 8 steps with an overall yield of 19%. The key steps are a thermal acid-promoted bicyclization of an ω-acetylenic amino ester and a Suzuki cross-coupling reaction between a heteroaryl triflate and (4-chlorophenyl)boronic acid.
- Cossy, Janine,Belotti, Damien
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p. 5145 - 5156
(2007/10/03)
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