Hydrogen bonding mediated enantioselective organocatalysis in brine: significant rate acceleration and enhanced stereoselectivity in enantioselective Michael addition reactions of 1,3-dicarbonyls to β-nitroolefins.
نویسندگان
چکیده
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.
منابع مشابه
Recyclable organocatalysis: highly enantioselective Michael addition of 1,3-diaryl-1,3-propanedione to nitroolefins.
The first Michael addition of 1,3-diaryl-1,3-propanedione to nitroolefins was demonstrated using a simple organocatalyst, which afforded excellent yields (81-97%) and enantioselectivities (90 to >99% ee); the catalyst and excess reactant can be reused seven times through a simple filtration operation.
متن کاملEnantioselective Stereodivergent Nucleophile‐Dependent Isothiourea‐Catalysed Domino Reactions
α,β-Unsaturated acyl ammoniums generated from the reaction of α,β-unsaturated 2,4,6-trichlorophenol (TCP) esters bearing a pendent enone with an isothiourea organocatalyst are versatile intermediates in a range of enantioselective nucleophile-dependent domino processes to form complex products of diverse topology with excellent stereoselectivity. Use of either 1,3-dicarbonyls, acyl benzothiazol...
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 کاملEnantioselective Synthesis of Succinimides by Michael Addition of 1,3-Dicarbonyl Compounds to Maleimides Catalyzed by a Chiral Bis(2-aminobenzimidazole) Organocatalyst
A wide variety of chiral succinimides have been prepared in high yields and enantioselectivities by an asymmetric conjugate addition of 1,3-dicarbonyl compounds to maleimides under very mild reaction conditions using the bifunctional benzimidazole-derived organocatalyst 5f. Computational and NMR studies support the hydrogen-bonding activation role of the catalyst and the origin of the stereosel...
متن کاملOrganocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines
Enantioselective organocatalysis has become a field of central importance within asymmetric chemical synthesis and appears to be efficient approach toward the construction of complex chiral molecules from simple achiral materials in one-pot transformations under mild conditions with high stereocontrol. This review addresses the most significant synthetic methods reported on chiral-amine-catalyz...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Chemical communications
دوره 47 34 شماره
صفحات -
تاریخ انتشار 2011