C 2 ‐Symmetric Cinchona Alkaloid Derivatives: Versatile Catalysts for the Enantioselective C−C Bond Forming Conjugate Addition of Nucleophiles to Simple α,β‐Unsaturated Acyl Pyrazoles

2020 ◽  
Vol 5 (48) ◽  
pp. 15190-15194
Author(s):  
Simon P. Curran ◽  
Brendan J. Fallon ◽  
Stephen J. Connon
Keyword(s):  
Conjugate Addition ◽  
Cinchona Alkaloid ◽  
Bond Forming ◽  
Unsaturated Acyl

Cinchona Alkaloid-Catalyzed Stereoselective Carbon-Carbon Bond Forming Reactions

2013 ◽  
Vol 2 (1) ◽  
pp. 47-67 ◽  
Author(s):  
Srinivasarao A. Babu ◽  
Ramasamy V. Anand ◽  
Sripada S.V. Ramasastry
Keyword(s):  
Cinchona Alkaloid ◽  
Carbon Bond ◽  
Bond Forming ◽  
Carbon Carbon Bond ◽  
Bond Forming Reactions

ChemInform Abstract: Cinchona Alkaloid-Catalyzed Stereoselective Carbon-Carbon Bond Forming Reactions

ChemInform ◽  
2014 ◽  
Vol 45 (40) ◽  
pp. no-no
Author(s):  
Srinivasarao A. Babu ◽  
Ramasamy V. Anand ◽  
Sripada S. V. Ramasastry
Keyword(s):  
Cinchona Alkaloid ◽  
Carbon Bond ◽  
Bond Forming ◽  
Carbon Carbon Bond ◽  
Bond Forming Reactions

NHC-Catalyzed Conjugate Addition Involving α,β-Unsaturated Acyl Azoliums

Synfacts ◽  
2009 ◽  
Vol 2009 (12) ◽  
pp. 1405-1405
Author(s):  
D. Lupton ◽  
S. Ryan ◽  
L. Candish
Keyword(s):  
Conjugate Addition ◽  
Unsaturated Acyl

scholarly journals Sequential catalysis: exploiting a single rhodium(i) catalyst to promote an alkyne hydroacylation–aryl boronic acid conjugate addition sequence

2017 ◽  
Vol 8 (1) ◽  
pp. 536-540 ◽  
Author(s):  
Maitane Fernández ◽  
Matthias Castaing ◽  
Michael C. Willis
Keyword(s):  
Boronic Acid ◽  
Conjugate Addition ◽  
Controlled Assembly ◽  
Bond Forming ◽  
Bond Forming Reactions ◽  
Acid Conjugate ◽  
Aryl Boronic Acid

We demonstrate that a single Rh(i) complex can promote two mechanistically distinct C–C bond-forming reactions – alkyne hydroacylation and aryl boronic acid conjugate addition – to deliver substituted ketone products from the controlled assembly of three readily available fragments.

Enantioselective Preparation of Alcohols and Amines:The Suh Synthesis of (-)-Macrosphelide J

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Conjugate Addition ◽  
Aliphatic Aldehyde ◽  
Geometric Control ◽  
Cinchona Alkaloid ◽  
University Of Virginia ◽  
Aliphatic Aldehydes ◽  
Salen Complex ◽  
Complementary Approach ◽  
National University ◽  
The University

Keiji Maruoka of Kyoto University (J. Am. Chem. Soc. 2009, 131, 3450) and Yujiro Hayashi of the Tokyo University of Science (Chem. Commun. 2009, 3083) independently developed organocatalysts for the enantioselective α-benzoylation of aliphatic aldehydes such as 1. The product 3 can be readily carried on to, inter alia, either enantiomer of the epoxide. Chengjian Zhu of Nanjing University designed (Adv. Synth. Cat. 2009, 351, 920) a chiral salen complex that mediated the enantioselective opening of both cyclohexene oxide (4) and cyclopentene oxide. This reagent combination might also engage just one of the two enantiomers of a racemic cycloalkene epoxide. Lin Pu of the University of Virginia established (Organic Lett. 2009, 11, 2441) a BINOL catalyst for the addition of ethyl propiolate 7 to an aliphatic aldehyde 6 to give the alcohol 8 in high ee. In a complementary approach, Do Hyun Ryu of Sungkyunkwan University found (Angew. Chem. Int. Ed. 2009, 48, 4398) that an oxazaborolidinium salt catalyzed the addition of 7 to 9 to give 10 with high ee and high geometric control. Jianliang Xiao of the University of Liverpool devised (J. Am. Chem. Soc. 2009, 131, 6967) an Ir catalyst for the enantioselective reductive amination of a ketone 11 to the amine 13 . Karl B. Hansen, Yi Hsiao. and Feng Xu, then all at Merck/Rahway, showed (J. Am. Chem. Soc. 2009, 131, 8798) that it was possible to hydrogenate a vinylogous primary amide 14 to the amine 15 with high enantiocontrol. Takashi Ooi of Nagoya University designed (J. Am. Chem. Soc. 2009, 131, 7242) a chiral P-spiro tetraaminophosphonium catalyst that mediated the enantioselective addition of anilines to nitroalkenes such as 16. The product 18 could be carried on to the 1,2-diamine, or to the α-amino acid. Masahiro Terada of Tohoku University devised (Angew. Chem. Int. Ed. 2009, 48, 2553) a BINOL-derived phosphonic acid to catalyze the enantioselective 1,2-addition of the enamide 20 to the imine derived from 19. Yixin Lu of the National University of Singapore found (Organic Lett. 2009, 11, 1721) that a cinchona alkaloid-derived thiourea effectively catalyzed the enantioselective conjugate addition of nitroalkanes such as 22 to the acceptor 23.

scholarly journals Switchable selectivity in Pd-catalyzed [3 + 2] annulations of γ-oxy-2-cycloalkenones with 3-oxoglutarates: C–C/C–C vs C–C/O–C bond formation

2019 ◽  
Vol 15 ◽  
pp. 1107-1115 ◽  
Author(s):  
Yang Liu ◽  
Julie Oble ◽  
Giovanni Poli
Keyword(s):  
Reaction Temperature ◽  
Temperature Increase ◽  
Bond Formation ◽  
Conjugate Addition ◽  
Bond Forming ◽  
At Will

Two complementary [3 + 2] annulation protocols between 3-oxoglutarates and cyclic γ-oxy-2-cycloalkenones, simply differing on the reaction temperature, are disclosed. These domino transformations allow C–C/O–C or C–C/C–C [3 + 2] annulations at will, via an intermolecular Pd-catalyzed C-allylation/intramolecular O- or C-1,4-addition sequence, respectively. In particular, exploiting the reversibility of the O-1,4-addition step, in combination with the irreversible C-1,4-addition/decarboxylation path, the intramolecular conjugate addition step could be diverted from the kinetic (O-alkylation) to the thermodynamic path (C-alkylation) thanks to a simple temperature increase. Crucial for the success of this bis-nucleophile/bis-electrophile [3 + 2] annulation is its well-defined step chronology in combination with the total chemoselectivity of the former step. This [3 + 2] C–C/O–C bond forming annulation protocol could be also extended to 1,3,5-triketones as well as 1,3-bis-sulfonylpropan-2-one bis-nucleophiles.

Cinchona alkaloid-based chiral catalysts act as highly efficient multifunctional organocatalysts for the asymmetric conjugate addition of malonates to nitroolefins

2015 ◽  
Vol 13 (40) ◽  
pp. 10216-10225 ◽  
Author(s):  
Veeramanoharan Ashokkumar ◽  
Ayyanar Siva
Keyword(s):  
Michael Addition ◽  
Quaternary Ammonium ◽  
Conjugate Addition ◽  
Quaternary Ammonium Salts ◽  
Cinchona Alkaloid ◽  
Ammonium Salts ◽  
Addition Reactions ◽  
Chiral Catalysts ◽  
Reaction Conditions ◽  
Highly Efficient

New pentaerythritol tetrabromide based chiral quaternary ammonium salts have been prepared and used as organocatalysts for enantioselective Michael addition reactions between various nitroolefins and Michael donors under mild reaction conditions with very good chemical yields and ee's.

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