Highly Enantioselective Fluorination of Unprotected 3-Substituted Oxindoles: One-Step Synthesis of BMS 204352 (MaxiPost)
摘要:
The catalytic enantioselective fluorination of N-H-free 3-substituted oxindoles was accomplished by a Sc(III)/N,N'-dioxide complex. Under mild reaction conditions, a series of 3-aryl- and 3-alkyl-3-fluoro-2-oxindoles were obtained in excellent yields (up to 98%) and enantioselectivities (up to 99% ee) by using N-fluorobisbenzenesulfonimide (NFSI) as the fluorination agent. MaxiPost was synthesized efficiently in 81% yield with 96% ee.
l-Proline-Catalyzed Asymmetric Michael Addition of 2-Oxindoles to Enones: A Convenient Access to Oxindoles with a Quaternary Stereocenter
作者:Svetlana Tsogoeva、Matthias Freund
DOI:10.1055/s-0030-1259527
日期:2011.3
A new organocatalytic approach for 1,4-conjugate addition of 2-oxindoles to α,β-unsaturated ketones using the combination of readily available and nonexpensive l-proline and achiral trans-2,5-dimethylpiperazine as catalytic system is provided. The reaction results in oxindole derivatives with vicinal quaternary and tertiary carbon centers in up to 99% yield and 91% ee.
Catalytic asymmetric α‐arylation of N‐unprotected 3‐substituted oxindoles with diaryliodoniumsalts has been realized by a chiral Lewis acid promoted electrophilic addition and aryl‐rearrangement process. Single C3‐arylated products containing a quaternary carbon center were generated in high enantioselectivity and reactivity.
aminated in good yields and with good to excellent enantioselectivities using di-tert-butylazodicarboxylate as the aminating agent. The procedure proved to be also efficient for the amination of 3-substituted benzofuranones, although with moderate results. A bifunctional role of the catalyst, acting as Brønsted base and hydrogenbonddonor, is proposed according to the experimental results observed.
The highly Z‐selective asymmetric conjugateaddition of 3‐substituted oxindoles to alkynyl carbonyl compounds has been developed by using scandium complexes of chiral N,N′‐dioxides under mild conditions. The thermodynamically unstable Z‐olefin derivatives were obtained in excellent yields and high enantiomeric and geometric control. The catalyst was also found to be effective in the asymmetric acetylenic
Michael Addition of N-Unprotected 2-Oxindoles to Nitrostyrene Catalyzed by Bifunctional Tertiary Amines: Crucial Role of Dispersion Interactions
作者:Christoph Reiter、Sònia López-Molina、Bernhard Schmid、Christian Neiss、Andreas Görling、Svetlana B. Tsogoeva
DOI:10.1002/cctc.201301052
日期:2014.3.5
Bifunctional thiourea‐ or sulfonamide‐derived tertiary aminescatalyze the enantioselective nitro‐Michaeladdition of N‐unprotected 3‐substituted 2‐oxindoles to nitrostyrene in up to 99 % yields, 94:6 er, and 87:13 dr. Overcoming the necessity to introduce and remove activating or protecting groups at the nitrogen moiety leads to a reduction of energy use, costs, and waste. Transition‐state geometries