Cu (I) Catalyzed One Pot S_N‐Click Reactions of Halogenated Coumarins and 1‐aza‐coumarins

Abstract

A one pot three component, copper catalyzed azide‐alkyne cycloaddition reaction has been employed for the synthesis of bis‐coumarinyl triazoles (A–D) using 4‐chloro, 4‐bromomethyl, 3‐bromoacetyl and 4‐bromomethyl‐1‐aza‐coumarins (I–IV), sodium azide, and coumarin propargyl ethers (V–IX) in moderate yields.

Cu‐Catalyzed Synthesis of Coumarin‐1,2,3‐Triazole Hybrids connected with Quinoline or Pyridine Framework**

“…6-Propargyloxyquinoline (2 a) is a new derivative prepared in 95 % yield from 6hydroxyquinoline and propargyl bromide under refluxing acetone for 18 h in the presence of K 2 CO 3 . Classical Coppercatalysts [22,[26][27][28] were screened under different reaction conditions (Table 1). At first, the reaction between 4-azidocoumarin (1) with 2 equivalents of 6-propargyloxyquinoline (2 a) in the presence of CuSO 4 .5H 2 O (10 mol%) as catalyst and sodium ascorbate (25 mol%) as reducing agent in acetone/water [27] (5 : 1) at r.t. for 1 d left unchanged the starting compound 2 a (Table 1, entry 1).…”

3‐Bromoacetylcoumarin, a Crucial Key for Facial Synthesis of Biological Active Compounds

“…Bis-coumarinyl triazoles (73) are synthesized in reasonable yields using a one-pot, three-component copper catalyzed azide-alkyne cycloaddition reaction involving 3-bromoacetylcoumarin (4), sodium azide and coumarin propargyl ether (72) (Scheme 18). [83] Savanur et al [84] identified another 1,2,3-triazolo-3-acetyl coumarin (73) with phenyl acetylene in aqueous PEG.…”

“…[83] (The scheme was redrawn from literature.) [83] Scheme 19. One-pot reaction of 3-acetylcoumarin (1) with heterylthiols (74) and benzothioles (76).…”

“…The bromination of 3-acetylcoumarin (1) is the starting point for the synthesis of coumarin thiazole derivatives (86). As a result, ethyl 4-(2-oxo-2H-chromen-3-yl)thiazole-2-carboxylate ( 84) is obtained in reasonable yield by treating 3-bromoacetylcoumarin (2) with ethyl thiooxamate (83). The intermediate 2-oxo-2H-chromen-thiazole-2-carbohydrazide ( 85) is then formed from reaction 84 with hydrazine hydrate.…”

“…Synthesis of coumarin-linked triazole derivatives (73). [83] (The scheme was redrawn from literature.) [83] Scheme 19.…”