L-Proline as an efficient and reusable promoter for the synthesis of coumarins in ionic liquid

Abstract

Abstract:The effect of L-proline as a promoter on the condensation reaction of salicylaldehyde or its derivatives with ethyl acetoacetate in neutral ionic liquid [emim]BF 4 was studied. All reactions were carried out under mild reaction conditions and achieved high yields. Moreover, the ionic liquid containing L-proline could be recycled and reused for several times without noticeably decreasing in productivity. The results show that the L-proline-[emim]BF 4 system has a potential in contribution to the development of environmentally friendly and inexpensive processes in organic syntheses.

ZnO nanoparticle as catalyst for efficient green one-pot synthesis of coumarins through Knoevenagel condensation

“…Also the identity of these compounds was established by comparison of their melting point with those of reported samples (table 1). 26,27,33…”

Ionic liquid assisted synthesis of six-membered oxygen heterocycles

“…The water solution containing l-proline was distilled under a reduced pressure, and the remaining ionic liquid containing l-proline was recycled and reused at least five times without noticeably decreasing the productivity. Compared with conventional methods, the l-proline-[emim]BF 4 system offers a clean, efficient, eco-friendly protocol for the synthesis of coumarins, with a high yield and a simple work-up procedure, and also a recyclable reaction medium [248] (Scheme 22).…”

Synthesis of 4-aryl-6-phenyl-3-cyano-2-pyridones Using l-Proline as an Organocatalyst

“…Our recent interest has been in the development of new synthetic methods on using l-proline as organo and recyclable catalyst. Recently, l-proline has utilized as versatile catalyst for variety of organic transformations such as the synthesis of coumarins in ionic liquid [35] and α-aminoxylation of aldehydes [36]. Also, l-proline and l-proline derivatives were successfully used as organo catalysts in asymmetric aldol and Michael addition reactions [37].…”