Silver-mediated synthesis of indolizines via oxidative C–H functionalization and 5-endo-dig cyclization

Abstract

An efficient strategy for the synthesis of indolizines from readily available starting materials via oxidative C-H functionalization and 5-endo-dig cyclization in one step has been demonstrated. This protocol represents wide substrate scope, high functional group tolerance and selectivity. The structure of the product was confirmed by the X-ray crystallographic studies. The Ag2CO3 required of this tandem reaction can be recycled and reused after undergoing oxidative reaction.

Access to Imidazole Derivatives by Silver(I) Carbonate Mediated Coupling of Vinyl Azides with Secondary Amines

“…In order to demonstrate the synthetic competence of our synthetic strategy, a gram‐scale (5 mmol) synthesis of 8a was performed. Compound 8a was obtained in 90 % yield in the gram‐scale reaction, and we could regenerate 80 % of the Ag 2 CO 3 used in the reaction according to a literature procedure 14. The regenerated Ag 2 CO 3 was used for further reactions, which showed the same catalytic efficiency as the fresh one.…”

Recent advances in the synthesis of indolizines and their π-expanded analogues

“…34 In contrast to the previous work, 33 higher yields were obtained when electron-rich alkynes were used as a starting material. 34 In contrast to the previous work, 33 higher yields were obtained when electron-rich alkynes were used as a starting material.…”

“…33 The presence of an ester group in the side chain of pyridine provided generally higher yields of 28. 33 The presence of an ester group in the side chain of pyridine provided generally higher yields of 28.…”

Recent Organic Transformations with Silver Carbonate as a Key External Base and Oxidant

“…Although the reaction mechanism is not clear, this reaction involves a unique β-C-C coupling and oxygen transposition of propargylic alcohols. The Agrawal group reported the synthesis of indolizines 12 via a Ag-mediated oxidative C-H functionalization and cyclization of terminal alkynes 1 with pyridine derivatives 11 (Scheme 7) [20]. Indolizine is a basic organic building block for many alkaloids and bioactive molecules, so the development of regioselective synthetic pathways is an attractive topic in organic synthesis [21].…”