A novel and facile carbodiimide-mediated synthesis of 2,3-dihydro-6H-pyrimido[2,1-b]quinazolin-4(1H)-ones via a tandem intramolecular nucleophilic addition/intramolecular hetero conjugate addition annulation strategy

1996 ◽  
Vol 37 (50) ◽  
pp. 9071-9072 ◽  
Author(s):  
Takao Saito ◽  
Kensaku Tsuda
Keyword(s):  
Nucleophilic Addition ◽  
Conjugate Addition

scholarly journals Organocatalytic enantioselective dearomatization of thiophenes by 1,10-conjugate addition of indole imine methides

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xingguang Li ◽  
Meng Duan ◽  
Peiyuan Yu ◽  
K. N. Houk ◽  
Jianwei Sun
Keyword(s):  
Hydrogen Bonding ◽  
Phosphoric Acid ◽  
Nucleophilic Addition ◽  
Acid Catalysis ◽  
Conjugate Addition ◽  
Mild Conditions ◽  
Rapid Construction ◽  
Chiral Phosphoric Acid ◽  
Cyclic Molecules ◽  
Selectivity Control

AbstractCatalytic asymmetric dearomatization (CADA) is a powerful tool for the rapid construction of diverse chiral cyclic molecules from cheap and easily available arenes. This work reports an organocatalytic enantioselective dearomatization of substituted thiophenes in the context of a rare remote asymmetric 1,10-conjugate addition. By suitable stabilization of the thiophenyl carbocation with an indole motif in the form of indole imine methide, excellent remote chemo-, regio-, and stereocontrol in the nucleophilic addition can be achieved with chiral phosphoric acid catalysis under mild conditions. This protocol can be successfully extended to the asymmetric dearomatization of other heteroarenes including selenophenes and furans. Control experiments and DFT calculations demonstrate a possible pathway in which hydrogen bonding plays an important role in selectivity control.

scholarly journals First Zinc Bromide Promoted Annulative Domino Reactions between Enamines and Cyclic Morita–Baylis–Hillman Alcohols: Synthesis of N,O-Ketals

Synlett ◽  
2020 ◽  
Vol 31 (13) ◽  
pp. 1282-1286
Author(s):  
Farhat Rezgui ◽  
Ghalia Bouhalleb ◽  
Ahmed Meddeb ◽  
Noura Fakhar Bourguiba ◽  
Julien Legros ◽  
...  
Keyword(s):  
Nucleophilic Addition ◽  
Conjugate Addition ◽  
Domino Reaction ◽  
Domino Reactions ◽  
Zinc Bromide ◽  
Iminium Ion

A new efficient ZnBr2-mediated annulative domino reaction between enamines and cyclic Morita–Baylis–Hillman (MBH) alcohols is disclosed. The process involves a tandem sequence (intermolecular conjugate addition of enamines to MBH alcohols and intramolecular nucleophilic addition of the hydroxyl moiety to the transiently generated iminium ion), affording the corresponding N,O-ketals diastereoselectively in good yields.

New methods in asymmetric catalysis based on new hemi-labile bidentate ligands

2008 ◽  
Vol 80 (5) ◽  
pp. 881-890 ◽  
Author(s):  
André B. Charette ◽  
Alexandre Côté ◽  
Jean-Nicolas Desrosiers ◽  
Isabelle Bonnaventure ◽  
Vincent N. G. Lindsay ◽  
...  
Keyword(s):  
Asymmetric Catalysis ◽  
Nucleophilic Addition ◽  
Conjugate Addition ◽  
Bidentate Ligands ◽  
New Methods ◽  
Conjugate Reduction ◽  
Nitro Derivatives

Chiral bidentate hemi-labile bis(phosphine) monoxide ligands were shown to be quite effective in various copper-catalyzed transformations. Among them, the nucleophilic addition to imines, the conjugate addition to α,β-unsaturated nitro derivatives, and the conjugate reduction of α,β-unsaturated sulfones generally gave good to excellent yields and high enantiomeric excesses.

Homochiral oxazolidin-2-ones and imidazolidin-2-ones by tandem nucleophilic addition–conjugate addition

2004 ◽  
Vol 15 (12) ◽  
pp. 1937-1943 ◽  
Author(s):  
Marco Ciclosi ◽  
Cristiana Fava ◽  
Roberta Galeazzi ◽  
Mario Orena ◽  
Maria Eugenia González-Rosende ◽  
...  
Keyword(s):  
Nucleophilic Addition ◽  
Conjugate Addition

Stereoselective, Base-Induced Formation of Bicyclo[2.2.1]heptanones and Bicyclo[3.2.1]octanols From the Products of Conjugate Addition of Lithiated Allylic Sulfoxides and Phosphine Oxides to Cyclopent-2-enone

1989 ◽  
Vol 42 (9) ◽  
pp. 1473 ◽  
Author(s):  
RK Haynes ◽  
AG Katsifis
Keyword(s):  
Low Temperature ◽  
Phosphine Oxide ◽  
Nucleophilic Addition ◽  
Ring Opening ◽  
Conjugate Addition ◽  
The Other ◽  
Side Chain ◽  
Lithium Diisopropylamide ◽  
Phosphine Oxides ◽  
Carbonyl Groups

Treatment of the neutral cyclopentanone adducts derived from the conjugate addition of each of lithiated 3-methylbut-2-enyl phenyl sulfoxide, (E)- and (Z)-but-2-enyldiphenylphosphine oxide to cyclopentenone with potassium t-butoxide results in intramolecular conjugate addition of the enolate arising from deprotonation at C5 of the cyclopentanone with the vinyl sulfoxide or phosphine oxide in the side chain togenerate bicyclo[2.2.l]heptanones in good yields. The use of an excess of lithium diisopropylamide at low temperature on the other hand results in kinetic deprotonation of the vinylic sulfoxide or phosphine oxide, and intramolecular nucleophilic addition of the resulting vinylic anions to the carbonyl groups in the respective adducts to generate bicyclo[3.2.l]octanols in acceptable yields. Application of the latter reaction to the lactone adduct of lithiated 3-methylbut-2-enyl phenyl sulfoxide and crotonolactone results in ring opening of the lactone to give a 2-(phenylsulfinyl)cyclohex-2-enone.

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