Papers

With Tag: General Organic Chemistry

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Catalytic Asymmetric Aldol-Type Reaction of Zinc Enolate Equivalent of Amides

Seijiro Matsubara, Ryosuke Haraguchi
Org. Lett. | 2013 | 10.1021/ol401425s

Treatment of phenyl isocyanate with bis(iodozincio)methane gave a zinciomethylenated product, which acts as an amide-enoate equivalent. It did not react with an aldehyde efficiently, but gave the corresponding adduct in good yield in the presence of an...

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Highly Enantioselective Copper-Catalyzed Propargylic Substitution of Propargylic Acetates with 1,3-Dicarbonyl Compounds

Yuan Zou, Song Chen, Xin-Hu Hu, Fu-Lin Zhu, Xiang-Ping Hu, Ya-Hui Wang, Fu-Zhong Han
Org. Lett. | 2013 | 10.1021/ol403469m

A chiral tridentate ketimine P,N,N-ligand has been successfully applied in the copper-catalyzed enantioselective propargylic substitution of propargylic acetates with a variety of β-dicarbonyl compounds, in which excellent enantioselectivities (up to >99% ee)...

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Utilization of Potassium Vinyltrifluoroborate in the Development of a 1,2-Dianion Equivalent

Deidre L. Sandrock, Gary A. Molander
Org. Lett. | 2009 | 10.1021/ol900822j

Previous studies of orthogonally reactive dibora species led to the discovery of a unique reactivity pattern associated with potassium vinyltrifluoroborate. Upon hydroboration, the vinyltrifluoroborate generates a 1,2-diboraethane, which is distinct from the...

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Dichloromethane Activation. Direct Methylenation of Ketones and Aldehydes with CH2Cl2 Promoted by Mg/TiCl4/THF

Chia-Chung Tsai, Ching-Ting Chien, Chia-Ching Cho, Pei-Chen Huang, Tu-Hsin Yan
Org. Lett. | 2004 | 10.1021/ol0478887

This Mg−TiCl 4 -promoted CH 2 -transfer reaction of CH 2 Cl 2 represents an extremely simple, practical, and efficient methylenation of a variety of ketones and aldehydes, especially in enolizable or sterically hindered ketones such as...

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Pipecolic Acid-Catalyzed Direct Asymmetric Mannich Reactions

Carlos F. Barbas, K. N. Houk, Rajee Thayumanavan, Paul Ha-Yeon Cheong, Fujie Tanaka, Haile Zhang
Org. Lett. | 2006 | 10.1021/ol052861o

Mannich reactions between aldehydes and N-p-methoxyphenyl-protected α-imino ethyl glyoxylate have been performed using (S)-pipecolic acid as catalyst. The reactions give both syn- and anti-products (dr = 1.4−2:1) with high enantioselectivities (>98% ee). In...

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Nickel-Catalyzed Enantioselective Cross-Couplings of Racemic Secondary Electrophiles That Bear an Oxygen Leaving Group

Alexander J. Oelke, Jianwei Sun, Gregory C. Fu
J. Am. Chem. Soc. | 2012 | 10.1021/ja300031w

To date, effective nickel-catalyzed enantioselective cross-couplings of alkyl electrophiles that bear oxygen leaving groups have been limited to reactions of allylic alcohol derivatives with Grignard reagents. In this Communication, we establish that, in the...

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Synthesis of Dialkyl Ethers from Organotrifluoroborates and Acetals

T. Andrew Mitchell, Jeffrey W. Bode
J. Am. Chem. Soc. | 2009 | 10.1021/ja906514s

The formation of ethers by C−O bond formation under harsh basic or acidic conditions is an entrenched synthetic disconnection in organic chemistry. We report a strategic alternative that involves the BF 3 ·OEt 2 -promoted coupling of stable, easily prepared...

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Acceleration Effect of Lewis Acid in Allylboration of Aldehydes:  Catalytic, Regiospecific, Diastereospecific, and Enantioselective Synthesis of Homoallyl Alcohols†

Tatsuo Ishiyama, Norio Miyaura, Taka-aki Ahiko
J. Am. Chem. Soc. | 2002 | 10.1021/ja0210345

The addition of pinacol allylboronic esters to aromatic and aliphatic aldehydes smoothly occurred at −78 °C in toluene in the presence of a catalytic amount of AlCl 3 or Sc(OTf) 3 (10 mol %) to give the corresponding homoallyl alcohols in high yields. The...

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Four-Component Reactions for a New Diastereoselective Synthesis of Chiral Quaternary Centers

Amal Shabli, Jos P. Varghese, Deborah Amsallem, Ilan Marek, Genia Sklute
J. Am. Chem. Soc. | 2003 | 10.1021/ja036872t

The one-pot preparation of chiral homoallylic alcohol and amine derivatives was easily achieved by carbocupration of alkynyl sulfoxides followed by an in situ zinc homologation and reaction with aldehydes or imines. In this process, three new carbon−carbon...

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Single-Step Process for the Reductive Deoxygenation of Unhindered Alcohols

Bin Zheng, Mohammad Movassaghi, Andrew G. Myers
J. Am. Chem. Soc. | 1997 | 10.1021/ja971768v

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Hydrogen-Bond-Mediated Enantio- and Regioselectivity in a Ru-Catalyzed Epoxidation Reaction

Carola Berthold, Felix Voss, Philipp Fackler, Thorsten Bach
J. Am. Chem. Soc. | 2010 | 10.1021/ja107601k

A chiral epoxidation catalyst based on a tricyclic octahydro-1H-4,7-methanoisoindol-1-one scaffold, in which a hydrogen bonding site and the catalytically active ruthenium center are spatially separated, was synthesized. It was shown that epoxidation...

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A General Method for Copper-Catalyzed Arene Cross-Dimerization

Hien-Quang Do, Olafs Daugulis
J. Am. Chem. Soc. | 2011 | 10.1021/ja2047717

A general method for a highly regioselective copper-catalyzed cross-coupling of two aromatic compounds using iodine as an oxidant has been developed. The reactions involve an initial iodination of one arene followed by arylation of the most acidic C–H bond of...

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Readily Accessible 9-epi-amino Cinchona Alkaloid Derivatives Promote Efficient, Highly Enantioselective Additions of Aldehydes and Ketones to Nitroolefins

Stephen J. Connon, Séamus H. McCooey
Org. Lett. | 2007 | 10.1021/ol0628006

Simple cinchona alkaloid derivatives, available via a one-pot procedure from commercially available starting materials, have been shown to promote highly enantio- and diastereoselective Michael-type addition reactions between enolizable carbonyl compounds and...

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An Approach to α-Keto Vinyl Carbinols

Samir Z. Zard, Marie-Gabrielle Braun
Org. Lett. | 2011 | 10.1021/ol103044x

Adducts from the radical addition of xanthates to ethyl vinyl sulfide readily undergo elimination of the xanthate group upon thermolysis to give vinylic and/or allylic sulfides, depending on the structure. In the case of α-xanthyl ketones, the adducts are...

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Enhancing Regiocontrol in Carboaluminations of Terminal Alkynes. Application to the One-Pot Synthesis of Coenzyme Q10

Tom Butler, Jeff Servesko, Asher Lower, Bruce H. Lipshutz
Org. Lett. | 2007 | 10.1021/ol701469e

Two new “generations” of methodological advances are reported for the Negishi carboalumination of terminal alkynes. Use of simple, inexpensive additives that alter the Al−Zr complex formed between Me 3 Al and Cp 2 ZrCl 2 give rise to an especially effective...

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Kinetic Resolution of Diols and Pyridyl Alcohols by Cu(II)(borabox)-Catalyzed Acylation

Clément Mazet, Andreas Pfaltz, Stephen Roseblade, Valentin Köhler
Org. Lett. | 2006 | 10.1021/ol060443t

Boron-bridged bisoxazoline (borabox) ligands have been used in the copper(II)-catalyzed benzoylation of pyridyl alcohols and 1,2-diols. Efficient kinetic resolution of 1,2-diols was achieved using both borabox and bisoxazoline (box) ligands. Borabox ligands...

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Palladium-Catalyzed Allylic Amination Using Aqueous Ammonia for the Synthesis of Primary Amines

Takashi Nagano, ShuÌ… Kobayashi
Journal of American Chemical Society | 2009 | 10.1021/ja900328x

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Palladium-Catalyzed Coupling of sp2-Hybridized Tellurides

Gilson Zeni, Hélio A. Stefani, Antonio L. Braga
Acc. Chem. Res. | 2003 | 10.1021/ar0202621

Vinylic tellurides are of importance due to their useful behavior as synthons and intermediates. Recently, the use of these compounds in place of vinylic halides or triflates in the palladium-catalyzed cross-coupling reaction has emerged as a powerful tool in...

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Enantioselective Free Radical Reactions

Ned A. Porter, Mukund P. Sibi
Acc. Chem. Res. | 1998 | 10.1021/ar9600547

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Highly Chemoselective Rhodium-Catalyzed Methylenation of Fluorine-Containing Ketones

Hélène Lebel, Valérie Paquet
Org. Lett. | 2002 | 10.1021/ol025730l

The rhodium(I)-catalyzed methylenation of functionalized fluorinated ketones using trimethylsilyldiazomethane proceeds to give the corresponding fluoromethylalkenes in good yields (61−90%). Remarkable chemoselectivity was observed for the synthesis of...

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