Chiral amine-thioureas bearing multiple hydrogen bonding donors: highly efficient organocatalysts for asymmetric Michael addition of acetylacetone to nitroolefins.
نویسندگان
چکیده
New bifunctional organocatalysts amine-thioureas bearing multiple hydrogen bonding donors were synthesized and applied in catalytic asymmetric Michael addition of acetylacetone to aryl and alkyl nitroolefins. Multiple hydrogen bonding donors play a significant role in accelerating reactions, improving yields and enantioselectivities.
منابع مشابه
Highly enantioselective Michael addition of diethyl malonate to chalcones catalyzed by cinchona alkaloids-derivatived bifunctional tertiary amine-thioureas bearing multiple hydrogen-bonding donors.
Chalcones are still challenge substrates in Michael reactions, and only limited success has been achieved. This work describes a highly enantioselective Michael addition of diethyl malonate with chalcones catalyzed by cinchona alkaloids-derivatived bifunctional tertiary amine-thioureas bearing multiple hydrogen-bonding donors.
متن کاملAsymmetric Michael Addition Organocatalyzed by α,β-Dipeptides under Solvent-Free Reaction Conditions.
The application of six novel α,β-dipeptides as chiral organocatalysts in the asymmetric Michael addition reaction between enolizable aldehydes and N-arylmaleimides or nitroolefins is described. With N-arylmaleimides as substrates, the best results were achieved with dipeptide 2 as a catalyst in the presence of aq. NaOH. Whereas dipeptides 4 and 6 in conjunction with 4-dimethylaminopyridine (DMA...
متن کاملCinchona alkaloid-based chiral catalysts act as highly efficient multifunctional organocatalysts for the asymmetric conjugate addition of malonates to nitroolefins.
New pentaerythritol tetrabromide-based chiral quaternary ammonium salts acting as organocatalysts (7a and 7b) have been prepared and used as organocatalysts for enantioselective Michael addition reactions between various nitroolefins and Michael donors (malonates) under mild reaction conditions, such as lower concentration of base and catalyst and room temperature, with very good chemical yield...
متن کاملHydrogen bonding mediated enantioselective organocatalysis in brine: significant rate acceleration and enhanced stereoselectivity in enantioselective Michael addition reactions of 1,3-dicarbonyls to β-nitroolefins.
Brine provides remarkable rate acceleration and a higher level of stereoselectivity over organic solvents, due to the hydrophobic hydration effect, in the enantioselective Michael addition reactions of 1,3-dicarbonyls to β-nitroolefins using chiral H-donors as organocatalysts.
متن کاملAn Efficient Synthesis of Enantiomerically Pure γ-Aminobutyric Acid (GABA) Derivatives
Chiral γ-aminobutyric acid (GABA) derivatives are the normal inhibitory neurotransmitters in the mammalian central nervous system. In this paper, enantiopure GABA derivatives 6 were synthesized via reduction/cyclization/hydrolysis cascade reactions from the highly enantioselective β-aryl-γnitroalkanes Michael adducts 4, which was obtained from asymmetric Michael addition of S, S’-diphenyldithio...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Chemical communications
دوره 12 شماره
صفحات -
تاریخ انتشار 2008