Asymmetric Synthesis of α-Fluoro-β-Amino-oxindoles with Tetrasubstituted C–F Stereogenic Centers via Cooperative Cation-Binding Catalysis
作者:Sushovan Paladhi、Sang Yeon Park、Jung Woon Yang、Choong Eui Song
DOI:10.1021/acs.orglett.7b02628
日期:2017.10.6
Biologically relevant chiral 3,3-disubstituted oxindole products containing a β-fluoroamine unit are obtained in high yields and with excellent stereoselectivity (up to 99% ee, dr >20:1 for syn) through the organocatalytic direct Mannich reaction of 3-fluoro-oxindoles as fluoroenolate precursors and α-amidosulfones as the bench-stable precursors of sensitive imines by using a chiral oligoethylene glycol
通过3-氟的有机催化直接曼尼希反应,可以高收率且具有出色的立体选择性(高达99%ee,syn的dr> 20:1 ),获得了具有β-氟胺单元的生物相关的手性3,3-二取代的羟吲哚产物。分别使用手性低聚乙二醇和KF作为阳离子结合催化剂和碱,将-oxindoles作为氟烯酸酯前体,将α-酰胺基砜作为敏感亚胺的替补稳定前体。该协议可以轻松扩展,而不会影响不对称感应。此外,该协议也已成功扩展到生成四取代的C–Cl和C–Br立体异构中心。