(Indolizinylethyl)-Substituted N-Sulfonyl Ketimines via an Imino-Alkyne Cyclization

What is it about?

The β-Csp3−H functionalization of N-sulfonyl ketimines with 2-(2-enynl)pyridines/quinolines via a cooperative Ag(I)-/organobase-catalyzed 5-endo-dig cyclization-addition reaction is reported. This successive C−N/C−C bond-making reaction provides a simple and atom-economical technique for granting a diverse set of 1,3-disubstituted indolizines/pyrrolo[1,2-a]quinolines possessing a synthetically resourceful N-sulfonyl ketimine moiety. Moreover, our designed strategy applies to broad substrates and allows various functionalities. Furthermore, this technique has many imperative synthetic points such as mild reaction conditions, low catalyst loading, acceptable chemical yields and highly diastereoselective (up to ≤93 : 7 dr). The N-sulfonyl ketimine moiety of indolizine was easily transmuted into the reputed classes of coumarin and benzofuran derivatives.

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Why is it important?

A series of α-(indolizinyl/pyrrolo[1,2-a]quinolinylethyl)-substituted N-sulfonyl ketimines were synthesized from α-alkyl N-sulfonyl ketimines and 2-(2-enynl)pyridines/quinolines using Ag(I)-/Et3N as a cooperative catalytic system is reported.