ChemInform Abstract: Formation of Quaternary Stereogenic Centers by NHC-Cu-Catalyzed Asymmetric Conjugate Addition Reactions with Grignard Reagents on Polyconjugated Cyclic Enones.

ChemInform ◽  
2012 ◽  
Vol 43 (45) ◽  
pp. no-no
Author(s):  
Matthieu Tissot ◽  
Daniele Poggiali ◽  
Helene Henon ◽  
Daniel Mueller ◽  
Laure Guenee ◽  
...  
Keyword(s):  
Conjugate Addition ◽  
Grignard Reagents ◽  
Addition Reactions ◽  
Stereogenic Centers ◽  
Cyclic Enones ◽  
Quaternary Stereogenic Centers

Formation of Quaternary Stereogenic Centers by NHC-Cu-Catalyzed Asymmetric Conjugate Addition Reactions with Grignard Reagents on Polyconjugated Cyclic Enones

2012 ◽  
Vol 18 (28) ◽  
pp. 8731-8747 ◽  
Author(s):  
Matthieu Tissot ◽  
Daniele Poggiali ◽  
Hélène Hénon ◽  
Daniel Müller ◽  
Laure Guénée ◽  
...  
Keyword(s):  
Conjugate Addition ◽  
Grignard Reagents ◽  
Addition Reactions ◽  
Stereogenic Centers ◽  
Cyclic Enones ◽  
Quaternary Stereogenic Centers

Asymmetric Conjugate Addition of α-Cyanoketones to Benzoyl Acrylonitrile Derivatives Using a Diaminomethylenemalononitrile Organocatalyst

Synthesis ◽  
2020 ◽  
Vol 52 (24) ◽  
pp. 3874-3880 ◽  
Author(s):  
Tsuyoshi Miura ◽  
Hiroshi Akutsu ◽  
Kosuke Nakashima ◽  
Yuta Kanetsuna ◽  
Masahiro Kawada ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Conjugate Addition ◽  
Significant Loss ◽  
Addition Reactions ◽  
Dicarbonyl Compounds ◽  
Stereogenic Centers ◽  
Synthetic Intermediates ◽  
Quaternary Stereogenic Centers

AbstractA diaminomethylenemalononitrile (DMM) organocatalyst was used to efficiently promote asymmetric conjugate addition of various α-cyanoketones to benzoyl acrylonitrile derivatives. The corresponding 1,5-dicarbonyl compounds containing vicinal tertiary and quaternary stereogenic centers are versatile synthetic intermediates and were obtained in good yields and with excellent enantioselectivities (up to 96% ee). The present study describes the first successful examples of asymmetric conjugate addition reactions of α-cyanoketones with benzoyl acrylonitriles. In addition, the DMM organocatalyst can be recovered and reused up to five times without significant loss of either catalytic activity or enantioselectivity.

Enantioselective Construction of Alkylated Centers

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Conjugate Addition ◽  
Enantioselective Hydrogenation ◽  
Harvard University ◽  
Grignard Reagents ◽  
Stereogenic Centers ◽  
The University ◽  
Stereogenic Center ◽  
Quaternary Stereogenic Centers ◽  
Peptide Catalyst ◽  
Acid Esters

Unsaturated half acid esters such as 1 are readily prepared by Stobbe condensation between dialkyl succinate and an aldehyde. Johannes G. de Vries of DSM and Floris P. J. T. Rutjes of Radboud University Nijmegen observed (Adv. Synth. Catal. 2008, 350, 85) that these acids were excellent substrates for enantioselective hydrogenation. Kazuaki Kudo of the University of Tokyo designed (Organic Lett. 2008, 10, 2035) a resin bound peptide catalyst for the transfer reduction of unsaturated aldehydes such as 3 , using 4 as the net H2 donor. Note that 5 was produced with high enantiocontrol from 3 that was a ~ 2:1 mixture of geometric isomers. Motomu Kanai and Masakatsu Shibasaki of the University of Tokyo devised (J. Am. Chem. Soc. 2008, 130, 6072) a chiral Gd catalyst that mediated the conjugate cyanation of enones such as 6 with high ee. Eric N. Jacobsen of Harvard University prepared (Angew. Chem. Int. Ed. 2008, 47, 1762) a dimeric Al salen catalyst that showed improved activity over the monomeric catalysts. Even congested imides such as 8 could be cyanated efficiently, delivering alkylated quaternary stereogenic centers. Takahiro Nishimura and Tamio Hayashi of Kyoto University optimized (J. Am. Chem. Soc. 2008, 130, 1576) the Rh*-catalyzed enantioselective conjugate addition of silyl acetylenes to enones such as 10, to give 12. Adriaan J. Minnaard and Ben L. Feringa of the University of Groningen devised (Angew. Chem. Int. Ed. 2008, 47, 398) conditions for the enantioselective 1,6-conjugate addition of alkyl Grignard reagents to diene esters such as the inexpensive ethyl sorbate 14. The product 16 incorporated, in addition to the newly formed stereogenic center, a geometrically defined E alkene. William S. Bechara and André B. Charette of the Université de Montréal found (Organic Lett. 2008, 10, 2315) that alkyl Grignard reagents could be induced to add with high enantioselectivity to pyridyl sulfones such as 17. In a different approach, Gregory C. Fu of MIT developed (J. Am. Chem. Soc. 2008, 130, 3302; J. Am. Chem. Soc. 2008, 130, 2756) conditions for the enantioselective alkenylation of racemic bromo esters such as 19, The latter reference is to the analogous enantioselective coupling of organozinc bromides with racemic allylic chlorides.

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