A New and Efficient Method for the Synthesis of Pyrimido[2,1-<i>b</i>]Benzothiazole Derivatives

Abstract

The one-pot three-component reaction of 2-aminobenzothiazole, benzaldehyde derivatives and <i>β</i>-ketoester, <i>β</i>-diketone or malonate derivatives in solvent-free conditions provides the corresponding pyrimido [2,1-<i>b</i>] benzothiazole derivatives at 60?C in 60% - 72% yields without using any catalyst in an optimistic time

Synthesis of pyrimido[2,1-b][1,3]benzothiazoles and [1,3]benzothiazolo[3,2-a]quinazolines via one-pot three-component reactions from 2-aminobenzothiazole, arylglyoxals and 1,3-dicarbonyl compounds

“…14 The reaction of 2-aminobenzothiazoles with various Michael acceptors, such as acetylenic compounds, 15,16 alkyl malonates, 8,17 and enaminones. 18 Moreover, organic and medicinal chemists have developed a series of multicomponent reactions (MCRs) for the synthesis of heterocyclic compounds and complex biologically-active compounds, [19][20] such as multi-component reaction of 2-aminobenzimidazole, benzaldehyde derivatives, and active methylene compounds, 6,[21][22] and various other methods. [23][24][25][26][27][28][29] However, some of these modern methods have significant limitations such as tedious workup procedures, low yields, and longer reaction times.…”

Preparation, characterization and use of new lignocellulose-based bio nanocomposite as a heterogeneous catalyst for sustainable synthesis of pyrimido benzazoles

“…Polycyclic fused-ring heterocycles containing nitrogen and sulfur atom, are of great importance, especially in the pharmaceutical fields, because of their abundance in nature and their diverse biological properties (26)(27)(28). One of these important compounds, the pyrimido benzazole which is synthesized through Biginelli-like reaction (29,30), was extensively studied for their medicinal applications such as antimicrobial, antifungal, antibacterial, antihypertensive, antiviral and anticancer activities (31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42). They are also potent HIV integrase inhibitors (25,43), LTD 4 receptor antagonists (34), and are also used for the treatment of bronchial asthma and neurodegenerative disease (37,39,44).…”

“…Therefore, synthesis of this compound has attracted notable interest and a number of studies have been conducted on their synthesis methods, hence the great diversity of methods of preparation were described in the literature. Besides some advantages, Biginelli reactions need harsh conditions (40) and according to some reports (31,45,46), low yield, long reaction time and harmful organic solvents are some disadvantages of this reaction.…”

Synthesis of substituted methylidenepyrimidobenzothiazolones as potential cytotoxic agents

“…6 Pyrimidobenzothiazol-4-ones 1 display interesting biological properties, for example anticancer, [9][10][11] antimicrobial, 2,4,9 antiallergic 6 or antifungal. 3,4 Syntheses of 2H-pyrimido [2,1-b] [1,3]benzothiazol-2-ones 2 are usually less effective and were accomplished in a three-component reaction of a substituted benzaldehyde, malonate and 2-aminobenzothiazole 12 or by heating 2-aminobenzothiazoles with propargylic acids, 13 but-2-yn-1,4-diates 14,15 or ethyl cyanoacetate. 16 Another method is a microwave-promoted reaction of 2-aminobenzothiazoles with Baylis-Hillman acetates.…”

“…In turn, addition of 2-aminobenzothiazole 3a to alkyl 2-arylidenemalonates proceeds via the imine nitrogen atom. 12 Reactions of 2-aminobenzothiazoles with 2-chloromethylidenemalonates have not been reported. To shed more light on the observed phenomenon, we performed the reaction of 2-diethoxyphosphoryl-3-methoxyacrylate 4 with 2-aminobenzothiazole 3a in THF, in the presence of pyridine and it turned out that the substitution product 5a was formed exclusively.…”