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.
Synthesis of 3-Alkyl-3-bromo-1-ethoxycarbonyl-1,3-dihydro-2<i>H</i>-indol-2-ones
作者:Egle M. Beccalli、Alessandro Marchesini
DOI:10.1055/s-1992-26084
日期:——
3-Alkyl-1,3-dihydro-2H-indol-2-ones 1 are converted to the coresponding 2-ethoxycarbonyloxy derivatives 2 by reaction with ethyl chloroformate in the presence of triethylamine. Bromination of 2 affords the title compounds in 73-93% yield.
A C(sp3)–H peroxidation of 3-substitutedindolin-2-ones through radical coupling reaction has been developed under metal-free conditions. Using tert-butyl hydroperoxide both as an oxidant and as a peroxidation reagent to couple with the C(sp3)–H bonds of 3-substitutedindolin-2-ones can form a new C–O bond without using any additives. This simple strategy provides a green and efficient approach to
artificial catalysts for asymmetric synthesis. Polyfunctional catalysts are considered to be a promising tool for achieving excellent catalytic efficiency. A polyfunctional catalyst system was developed, which incorporates two Lewisacidic/Brønsted basic cobalt centers in combination with triazolium moieties that are crucial for high reactivity and excellent stereoselectivity in the direct1,4‐addition of
Tetrabutylammonium Iodide–Promoted Thiolation of Oxindoles Using Sulfonyl Chlorides as Sulfenylation Reagents
作者:Xia Zhao、Aoqi Wei、Xiaoyu Lu、Kui Lu
DOI:10.3390/molecules22081208
日期:——
of oxindoles using sulfonylchlorides as sulfenylation reagents. The above reaction was promoted by iodide anions, which was ascribed to the in situ conversion of sulfenyl chlorides into the more reactive sulfenyl iodides. Moreover, the thiolation of 3-aryloxindoles was facilitated by bases. The use of a transition-metal-free protocol, readily available reagents, and mild reaction conditions make this