Catalytic Asymmetric Umpolung Tandem Reactions of Hemiacetals via Dinuclear Zinc Cooperative Catalysis

Abstract

The umpolung activity of hemiacetals serving as α-carbon nucleophiles has been reported via dinuclear zinc cooperative catalysis. This umpolung strategy has been applied to catalytic asymmetric tandem reactions of 1-tosylindoline-2,3-diols with β,γ-unsaturated-α-keto compounds, providing a broad series of structurally diverse tetrahydrofuran spiro­oxindoles and dihydrofurans, respectively. In addition, products could be transformed to quinazoline and quinoline derivatives.

Reversal of enantioselectivity by tuning the ring size of ProPhenol

“…32–42 The excellent performance of this ligand also attracted our attention. 43–49 In 2014, we reported the ProPhenol analogue ( S , S )- L 4 as a new addition to the chiral aza-crown family by replacing the prolinol moieties with chiral azetidines (Fig. 1C).…”

Modular synthesis of 3,3-disubstituted oxindoles from nitrones and acrylic acids

“…Intramolecular annulation methods, including Heck-type coupling, [41][42][43][44][45][46][47][48][49][50] Friedel-Crafts reactions [51][52][53][54][55][56][57] and C(sp 2 )-H/C (sp 3 )-H coupling, [58][59][60] have emerged as alternative approaches (Scheme 1A, eqn (c) and (d)). These methods are efficient in forming 3,3-disubstituted oxindoles with highly functionalised benzenoid moieties.…”