A catalytic asymmetric carbonyl-ene reaction of [small beta],[gamma]-unsaturated [small alpha]-ketoesters with 5-methyleneoxazolines was accomplished. The process was based on the utilization of a chiral N,N'-dioxide/MgII catalyst, providing the desired products with excellent...
Here we report an efficient asymmetric [4+2] cycloaddition of β,γ-unsaturated α-ketoesters with cyclobutenones. The corresponding products were obtained in good yields (up to 92%) with excellent enantioselectivities (up to 98% ee) and diastereoselectivities (up to >19/1 dr). Moreover, based on the control experiments and previous reports, a possible catalytic cycle was proposed.
The asymmetric Cu(<scp>ii</scp>)–indolinylmethanol complex catalyzed Diels–Alder reaction of 2-vinylindoles with β,γ-unsaturated α-ketoesters: an efficient route to functionalized tetrahydrocarbazoles
作者:Banlai Ouyang、Tingting Yu、Renshi Luo、Gui Lu
DOI:10.1039/c4ob00196f
日期:——
An efficient asymmetric Diels–Alder reaction of 2-vinylindoles with β,γ-unsaturatedα-ketoesters has been developed for the construction of functionalized tetrahydrocarbazoles. The products were obtained in high yields (up to 96%) with good stereoselectivities (ee up to 95%, dr up to >99 : 1).
Asymmetric Hetero-Diels-Alder Reaction of Danishefsky’s Diene with α-Ketoesters and Isatins Catalyzed by a Chiral<i>N</i>,<i>N′</i>-Dioxide/Magnesium(II) Complex
A highly enantioselective hetero‐Diels–Alder reaction of Danishefsky’s diene with α‐ketoesters and isatins has been realized by using a chiral N,N′‐dioxide/MgII complex. In the presence of only 0.1–0.5 mol % catalyst, a series of substrates were transformed into the corresponding tetrasubstituted 2,3‐dihydropyran‐4‐ones in up to 99 % yield and more than 99 % ee in two hours.
You can count on the anion: Simply swapping the anions of an indium Lewis acid leads to a remarkable regioselectivity switch between asymmetric 1,2‐ and 1,4‐addition reactions. N‐protected indoles and β,γ‐unsaturated α‐keto esters gave adducts with excellent enantioselectivity (see scheme).