Organocatalytic asymmetric Michael-type reaction between β,γ-unsaturated α-keto ester and α-nitro ketone.
نویسندگان
چکیده
A Michael-type reaction of β,γ-unsaturated α-keto ester and α-nitro ketone was established. With a thiourea catalyst derived from cinchona alkaloid, the reactions afford products in 47-94% yields with 68-96% ee.
منابع مشابه
Organocatalytic asymmetric direct vinylogous Michael addition of α,β-unsaturated γ-butyrolactam to nitroolefins.
The first organocatalytic enantioselective direct vinylogous Michael reaction of α,β-unsaturated γ-butyrolactam to nitroolefins is developed using cinchona alkaloids as the catalysts. Both product enantiomers are accessible with moderate to good enantioselectivity.
متن کاملα-Ketophosphonates as ester surrogates: isothiourea-catalyzed asymmetric diester and lactone synthesis.
Isothiourea HBTM-2.1 catalyzes the asymmetric Michael addition/lactonization of aryl- and alkenylacetic acids using α-keto-β,γ-unsaturated phosphonates as α,β-unsaturated ester surrogates, giving access to a diverse range of stereodefined lactones or enantioenriched functionalized diesters upon ring-opening.
متن کاملTrienamine-mediated asymmetric [4+2]-cycloaddition of α,β-unsaturated ester surrogates applying 4-nitro-5-styrylisoxazoles.
Highly enantioselective organocatalytic [4+2]-cycloaddition of in situ generated trienamines with 4-nitro-5-styrylisoxazoles as α,β-unsaturated ester surrogates is presented. The synthetic utility of this strategy is demonstrated by transforming the formed cycloadducts into optically active carboxylates.
متن کاملCatalytic highly asymmetric 1,5(6)-selective cyclization reaction of α-hydroxyimino cyclic ketones: direct approach to ring-fused hydroxyimino dihydropyrans.
Herein, we have disclosed a catalytic asymmetric 1,5(6)-selective Michael/cyclization reaction of α-hydroxyimino cyclic ketones with γ,β-unsaturated α-keto esters. Unlike the previous catalytic strategies, this reaction provides a convenient 1,5(6)-selective asymmetric pathway to access synthetically useful ring-fused dihydropyrans. In general, high levels of yield, enantio- and diastereoselect...
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 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 & biomolecular chemistry
دوره 9 23 شماره
صفحات -
تاریخ انتشار 2011