Synthesis of Fused pyrazolo[4,3‐c]quinolines through KI‐Promoted Cyclization of Pyrazole‐arylamines and Benzyl Bromide

Abstract

A simple and highly efficient protocol was developed for the formation of pyrazolo [4,3-c]quinolines starting from 2-(1Hpyrazol-5-yl)anilines and benzyl bromide in the presence of KI, affording desired products in moderate to good yields. The reaction showed good tolerance for a range of substrates with variable substituents. In this methodolgy, benzyl bromide proved to be an available C1 synthon in organic synthesis. Moreover, benzyl bromide can be replaced with benzyl iodide to synthesize pyrazolo[4,3-c]quinoline derivatives, and benzyl chloride could not apply in this reaction system.

Visible light-mediated synthesis of quinazolinones from benzyl bromides and 2-aminobenzamides without using any photocatalyst or additive

“…Benzyl bromide, a multifunctional C1 synthon, is a simple precursor that has been successfully used in various transformations. [31][32][33] It has also been applied in the synthesis of quinazolinone compounds. For example, benzyl bromide and 2-aminobenzamide were utilized as substrates, and K 2 CO 3 was added to the reaction mixture and heated to 90 °C followed by the gradual addition of benzyl bromide and 2-aminobenzamide (Scheme 2b).…”