- Palladium-Catalyzed Asymmetric 1,6-Addition of Diarylphosphines to Allylidenemalonates for Chiral Phosphine Synthesis
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A pincer-palladium-catalyzed asymmetric 1,6-addition of diarylphosphines to allylidenemalonates has been developed for the synthesis of chiral allylic phosphines with up to 89% ee under mild conditions.
- Wei, Xu,Lu, Junzhu,Duan, Wei-Liang
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- Tellurium-Assisted Cycloprpanation and Alkylidenation of α,β-Unsaturated Carbonyl Compounds with Dibromomalonic Esters
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Dibutyl telluride assists cyclopropanation of α,β-unsaturated ketone, ester, and nitrile with dibromomalonic esters without solvent at room temperature.In addition, it effects alkylidenation of aldehydes including α,β-unsaturated aldehyde with the same reagent.
- Matsuki, Toshiaki,Hu, Nan Xing,Otsubo, Tetsuo,Ogura, Fumio
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- Divergent Rearrangements of Vinylcyclopropane into Skipped Diene and Cyclopentene: Mechanism, Scope, and Limitations
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Vinylcyclopropanes are versatile intermediates in organic synthesis which undergo various rearrangements. We report a new rearrangement of vinylcyclopropane into skipped diene. A detailed mechanistic study revealed that this transformation involves regioselective ring-opening of the cyclopropane ring followed by 1,2-migration of one of the cyclopropane substituents. Interestingly, our investigations showed that skipped diene is the kinetic product of the process but formation of a more stable cyclopentene is also accessible. The fundamental understanding of the processes involved enabled the development of divergent methodologies allowing to obtain cyclopentene or skipped diene from vinylcyclopropane in a selective and controlled manner.
- Delbrassinne, Arnaud,Richald, Maximilien,Janssens, Julien,Robiette, Rapha?l
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supporting information
p. 2862 - 2868
(2021/06/11)
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- Copper-catalyzed regiodivergent 1,4-and 1,6-conjugate silyl addition to diendioates: Access to functionalized allylsilanes
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A copper-catalyzed regioselective 1,4-and 1,6-conjugate addition of a silyl reagent to diendioates was established. Various 1,4-and 1,6-protosilylation products were obtained in good yields and with high regioselectivity via tuning the ligands used in the reactions. This protocol has provided a simple and efficient method for the synthesis of multisubstituted functionalized allylsilanes.
- Ahmad, Tanveer,Li, Qi,Qiu, Sheng-Qi,Xu, Jian-Lin,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 6122 - 6126
(2019/07/03)
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- Ring-Opening of Vinylcyclopropane-1,1-dicarboxylates by Boronic Acids under Ligandless Palladium Catalysis in Neat Water
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We report a highly efficient ring-opening reaction of vinylcyclopropanes by boronic acids in water, using palladium nanoparticles formed from Pd(OAc)2 under ligandless conditions. Unsubstituted vinylcyclopropanes provide linear addition products with high selectivity, while a switch in regioselectivity to branched products is observed for aryl-substituted vinylcyclopropanes.
- Yin, JieXiang,Hyland, Christopher J. T.
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p. 6529 - 6536
(2015/10/06)
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- Organocatalytic asymmetric annulation of 1,3-bis(alkoxycarbonyl)buta-1,3- dienes and aldehydes
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Asymmetric organocatalytic annulation of E/Z isomeric mixtures of bis(alkyl carboxylate)buta-1,3-dienes and aldehydes has been realized via enamine catalysis. In the presence of α,α-diphenyl-2-pyrrolidinemethanol trimethylsilyl ether, excellent stereo- and enantioselectivities were achieved for a broad spectrum of substrates.
- Pezzati, Bernardo,Chellat, Mathieu F.,Murphy, John J.,Besnard, Celine,Reginato, Gianna,Stephens, John C.,Alexakis, Alexandre
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supporting information
p. 2950 - 2953
(2013/07/26)
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- Asymmetric michael addition of ketones to alkylidene malonates and allylidene malonates via enamine - Metal lewis acid bifunctional catalysis
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Novel enamine-metal Lewis acid bifunctional catalysts were successfully applied to the asymmetric Michael addition of ketones to alkylidene malonates, offering excellent stereoselectivity (up to >99% ee and >99:1 dr). The asymmetric Michael addition of ketones to allylidene malonates was also achieved.
- Liu, Lu,Sarkisian, Ryan,Xu, Zhenghu,Wang, Hong
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supporting information
p. 7693 - 7699
(2012/11/07)
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- Natural α-amino acid l-lysine-catalyzed knoevenagel condensations of α,β-unsaturated aldehydes and 1,3-dicarbonyl compounds
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Knoevenagel condensations of α,β-unsaturated aldehydes and 1,3-dicarbonyl compounds were catalyzed by primary natural amino acid L-lysine. The reactions were carried out at room temperature in dimethylsulfoxide. It provides a facile entry to a wide variety of α,β,γ,δ- unsaturated dicarbonyl compounds. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
- He, Yan-Hong,Hu, Ying,Guan, Zhi
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experimental part
p. 1617 - 1628
(2011/06/21)
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- A dimethylsulfonium methylide mediated highly regioselective olefination of conjugated polyolefin 1,1-dioates to conjugated polyene-2-yl-malonates and their applications in Diels-Alder reactions
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The reactions between dimethylsulfonium methylide and 1,3-diene- or 1,3,5-triene-1,1-dioates under specific conditions enable the highly regioselective tandem ylide addition-eliminative olefination to provide 1,3-butadien-2-yl- or 1,3,5-hexatriene-2-yl-malonates. Alkylation at malonate methine carbon of 1,3-butadien-2-ylmalonates with a suitable alkyl halide having in-built functionalities for a dienophile generation led to quick assembly of precursors for type 2 intramolecular Diels-Alder reaction. Syntheses of functionalized bicyclo[n.3.1] alkenes (n=5 or 6) with the double bond at the bridgehead position have been achieved via the IMDA. An asymmetric version of this reaction has been developed using a MacMillan's imidazolidinone catalyst, which provided a bicyclo[5.3.1] alkene with very high enantioselectivity. In situ methylation at malonate methine carbon of 1,3,5-hexatriene-2-yl-malonates followed by intermolecular Diels-Alder reaction with N-methylmaleimide provided the cycloadduct with complete regiocontrol and high diastereoselectivity.
- Singh, Rekha,Ghosh, Sunil K.
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supporting information; experimental part
p. 2284 - 2292
(2010/06/16)
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- A nBuLi-mediated, expeditious and stereoselective ring-opening rearrangement of (arylmethylene)cyclopropane-1,1-dicarboxylates
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We report herein an nBuLi-mediated, expeditious, ring-opening rearrangement of (arylmethylene)cyclopropane 1,1-diesters to prepare 1,3-diene derivatives with good stereo-selectivity. The reaction mechanism has also been discussed.
- Hu, Bao,Jiang, Linan,Ren, Jun,Wang, Zhongwen
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experimental part
p. 1358 - 1363
(2010/04/29)
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- 1,6-Conjugate addition of boronic acids to 2-allylidenemalonates
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The addition of boronic acids to 2-allylidenemalonates under RhI or Pd2+ catalysis shows an enhanced selectivity for the 1,6-addition reaction in comparison with diunsaturated monoesters. In the case of the RhI-catalyzed addition, the position of the new C=C double bond in the final product can be tuned with the choice of the base to give vinylmalonates of alkylidenemalonates. Georg Thieme Verlag Stuttgart.
- De La Herrán, Gabriela,Csák?, Aurelio G.
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body text
p. 585 - 588
(2009/07/09)
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- Regioselective tandem dimethylsulfonium methylide addition - Eliminative olefination of diendioates: A novel route to 1,3-butadien-2-ylmalonates
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The appropriate choice of dimethylsulfonium methylide generation conditions enables the highly regioselective tandem ylide addition-eliminative olefination to 1,3-dienedioates providing 1,3-butadien-2-ylmalonates, a novel class of 2-substituted 1,3-dienes suitable for quick assembly of precursors for type 2 intramolecular Diels-Alder reactions.
- Singh, Rekha,Ghosh, Sunil K.
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p. 5071 - 5074
(2008/03/28)
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- Ionic liquid as catalyst and reaction medium - A simple, efficient and green procedure for Knoevenagel condensation of aliphatic and aromatic carbonyl compounds using a task-specific basic ionic liquid
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The basic ionic liquid 1-butyl-3-methylimidazolium hydroxide, [bmIm]OH, efficiently catalyzes Knoevenagel condensation without requirement of any organic solvent. A wide range of aliphatic and aromatic aldehydes and ketones easily undergo condensations with diethyl malonate, malononitrile, ethyl cyanoacetate, malonic acid and ethyl acetoacetate. The reactions proceed at room temperature and are very fast (10-30 min). However, the most significant feature of this methodology is the condensation of aliphatic aldehyde with diethyl malonate, which is not very easy to achieve by conventional reagents, and was not addressed adequately in literature providing a general and convenient procedure. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Ranu, Brindaban C.,Jana, Ranjan
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p. 3767 - 3770
(2007/10/03)
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- Evidence of transannular bonding interaction between two sulfur atoms on photolysis of naphtho[1,8-ef][1,4]dithiepins
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Naphtho[1,8-ef][1,4]dithiepins 5 were prepared by the reaction of naphtho[1,8-de]-1,3-dithiins 3 with diethyl diazomalonate in the presence of copper acetylacetonate. The X-ray crystallographic analysis of 2,3-dihydro-2,2-bis(ethoxycarbonyl)-3-phenylnaphtho[1,8-ef][1,4]dithie pin (5a) revealed that the S···S distance is shorter than the sum of their van der Waals radii, indicating that compounds 5 have a strong through-space interaction between the two sulfur atoms. Direct irradiation of 5 with a 500 W high-pressure mercury lamp (313 nm) at room temperature gave the corresponding olefins 6 and naphtho[1,8-cd]-1,2-dithiole (1) quantitatively. The quantum yields of the consumption of 5a and the formation of 6a and 1 were 0.34. The mechanism of this reaction was investigated by examining the effect of sensitization and light intensity. The results indicate that the reaction may proceed by a one-photon process from an excited singlet state. Ab initio calculations were carried out on model compound 7, and it was shown that the excitation to the S1 state causes a bonding interaction between the two sulfur atoms, making the reaction possible.
- Fujii, Takayoshi,Takahashi, Ohgi,Furukawa, Naomichi
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p. 6233 - 6239
(2007/10/03)
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- REACTIONS OF TITANIUM DERIVATIVES OF CERTAIN CH ACIDS WITH CARBONYL COMPOUNDS. I. CROTONIC CONDENSATIONS WITH THE TITANIUM DERIVATIVES OF MALONIC ESTER, CYANOACETIC ESTER, AND MALONONITRILE
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The titanium derivatives of malonic ester, cyanoacetic ester, and malononitrile obtained by the reaction of the corresponding sodium salts with (i-PrO)3TiCl, react with aldehydes in THF at -78 to 20 deg C, forming the products from crotonic condensation.If α,β-unsaturated aliphatic α-bromo and keto aldehydes are used, the yields of the corresponding alkylidenemalonic and alkylidenecyanoacetic esters are substantially higher than under the conditions of the Knoevenagel reaction.
- Kasatkin, A. N.,Biktimirov, R. Kh.,Tolstikov, G. A.,Khalilov, L. M.
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p. 1029 - 1037
(2007/10/02)
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- α,β-Unsaturated esters from the tri-n-butylarsine-promoted reaction of bromomalonic esters with aldehydes
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A convenient synthesis of α,β-unsaturated esters (in 68-96percent yields) from the reaction of a bromomalonic ester with aldehydes promoted by tri-n-butylarsine is descriebed.A mechanism involving halophilic attack of tri-n-butylarsine leading to the formation of a salt followed by reaction with carbonyl compounds is proposed.This methodology provides a convenient route to α,β-unsaturated esters and represents an alternative to the Knoevenagel reaction.
- Shen, Yanchang,Yang, Baozhen
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