Asymmetric Michael addition mediated by novel cinchona alkaloid-derived bifunctional catalysts containing sulfonamides.
نویسندگان
چکیده
Novel cinchona alkaloid-derived bifunctional organocatalysts containing sulfonamide groups were utilized to promote Michael addition of bicyclic alpha-substituted beta-ketoesters to nitroolefins. The desired Michael adducts with all-carbon quaternary centers were constructed in high yield and with excellent enantioselectivity, demonstrating the great potential of cinchona alkaloid-derived sulfonamides in asymmetric catalysis.
منابع مشابه
Asymmetric catalysis with bifunctional cinchona alkaloid-based urea and thiourea organocatalysts.
Cinchona alkaloid derivatives modified to include a (thio)urea component have emerged in the last three years as readily accessible, robust and tunable bifunctional organocatalysts for a range of synthetically useful transformations. The origins of these catalysts and the major developments in their application in enantioselective synthesis are reviewed.
متن کاملOrganocatalytic asymmetric oxy-Michael addition to a γ-hydroxy-α,β-unsaturated thioester via hemiacetal intermediates.
We report an asymmetric oxy-Michael addition to a γ-hydroxy-α,β-unsaturated thioester via hemiacetal intermediates in the presence of Cinchona-alkaloid-thiourea-based bifunctional organocatalysts. This method provides a novel enantioselective route to β-hydroxy carboxyl compounds, which in turn can be used to synthesize valuable chiral building blocks.
متن کاملHighly enantioselective Michael addition of 3-arylthio- and 3-alkylthiooxindoles to nitroolefins catalyzed by a simple cinchona alkaloid derived phosphoramide.
A new cinchona alkaloid derived bifunctional tertiary amine-phosphoramide is identified as a highly enantioselective catalyst for Michael addition of both unprotected 3-arylthio- and 3-alkylthiooxindoles to nitroolefins. The phosphoramide moiety of plays an indispensable role in this reaction.
متن کاملAsymmetric generation of fluorine-containing quaternary carbons adjacent to tertiary stereocenters: uses of fluorinated methines as nucleophiles.
Organocatalytic asymmetric Michael reactions of fluorinated nucleophiles with nitroolefins catalyzed by Cinchona alkaloid-derived thiourea catalysts generated the desired Michael products containing vicinal fluorinated quaternary and tertiary chiral centers with exceptional enantioselectivity.
متن کاملNovel thiourea-amine bifunctional catalysts for asymmetric conjugate addition of ketones/aldehydes to nitroalkenes: rational structural combination for high catalytic efficiency.
A series of thiourea-amine bifunctional catalysts have been developed by a rational combination of prolines with cinchona alkaloids, which are connected by a thiourea motif. The catalyst 3a, prepared from L-proline and cinchonidine, was found to be a highly efficient catalyst for the conjugate addition of ketones/aldehydes to a wide range of nitroalkenes (up to 98/2 dr and 96% ee). The privileg...
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:
- Organic letters
دوره 11 2 شماره
صفحات -
تاریخ انتشار 2009