Asymmetric catalytic alkylation of vinyl azides with 3-bromo oxindoles: water-assisted chemo- and enantiocontrol

Asymmetric catalytic Friedel–Crafts alkylation with arenes and heteroarenes: construction of 3,3-disubstituted oxindoles

“…Based on the previous reports, 15–17 a plausible catalytic cycle and a stereo-control model have been proposed (Fig. 2).…”

“…2 q Also, our group has used 3-bromo-3-substituted oxindoles in aldol type, amination, alkylation and cycloaddition reactions. 15…”

Water-enabling strategies for asymmetric catalysis

“…In 2022, Feng and colleagues developed a novel asymmetric conjugate addition/water addition/elimination tandem reaction of vinyl azides with 3-bromo-3-substituted oxindoles by using a chiral N , N ′-dioxide L-PiOEt /Ni(OTf) 2 complex as the catalyst (Scheme 24). 44 Hydrated Na 3 PO 4 and free water were crucial for achieving high regioselectivity and enantioselectivity. The hydrated Na 3 PO 4 acted as a: (i) base for generation of indol-2-one species; (ii) reservoir to regulate the amount of water in the solution.…”

A Remarkable Influence of La(III)/N,N′-Dioxide Structure on Asymmetric Formal Substitution of 3-Bromo-3-substituted Oxindoles with TMSCN

“…Motivated by the importance of 3-cyano-substituted oxindoles and inspired by the reactivity of 3-bromo-3-substituted oxindole, we envisioned that the formal substitution reaction of 3-bromo-3-substituted oxindoles with TMSCN was feasible for facile construction of enantioenriched 3-cyano-oxindoles. In the presence of an exogenous base, 3-bromo-3-substituted oxindole transformed into an indol-2-one intermediate accompanied with the generation of HBr, which was activated by a chiral N , N ′-dioxide/metal complex.…”