Stereoselective synthesis of C3-tetrasubstituted oxindoles via copper catalyzed asymmetric propargylation

Abstract

Herein, a copper catalyzed asymmetric propargylation of 2-oxindole-3-carboxylate esters with terminal propargylic esters is described.

Asymmetric Propargylic C−C Bond Formation Using Metal–Allenylidene Species

“…A variety of substituted propargyl carbonates were suitable for this reaction, irrespective of the electronic property and steric hindrance of the substituents. The low reactivity of the alkyl-substituted propargyl carbonate reported in the previous literature [38] was also involved in the reaction and the target product 114 c was obtained in 59 % yield with 91 % ee. It is worth noting that a number of heterocyclic substituted propargyl carbonates such as pyrrole, pyridine, thiophene, furan and indoles were also suitable for the current catalytic system and reacted with 5H-thiazol-4-ones 112 to give the target products with good results (up to 96 % yield, 16 : 1 dr and 93 % ee).…”

“…[37] The use of 3-monosubstituted oxindoles to react with electrophiles was reported as an efficient way to access 3,3-disubstituted oxindoles. Given that, Zhang's group [38] developed the asymmetric propargylic alkylation of propargylic esters 61 with 2-oxoindoline-3-carboxylate 82 catalyzed by CuI/ L6 complex. This process provided a promising method for construction of 3,3-disubstituted oxindoles 83 bearing a terminal alkynyl group and adjacent tertiary and quaternary stereocenters (Scheme 25).…”