One-step conversions of esters to 2-imidazolines, benzimidazoles and benzothiazoles by aluminum organic reagents

Abstract

Aluminum organic reagents play an increasingly important role in effecting simple chemical transformations.Several examples, recently published, include conversions of esters to thioesters,1 ketene thioacetals,2 and amides,3 of esters to nitriles,4 and of epoxides to amino alcohols.5

Activated fly ash catalyzed facile synthesis of novel spiro imidazolidine derivatives as potential antibacterial and antifungal agents

“…Several methods have been reported for the synthesis of imidazolidines [29][30][31][32][33][34][35] which include conversion of esters using aluminium reagents 29 , the reaction between N-ethoxy carbonylthioamides with 1,2-diamines 30 and the reaction of aldehydes with 1,2-diamines followed by N-halosuccinimides 31 . Recently, several method have been developed where azalactones 32 , 2-aryl-1, 1-dibromoethanes 33 , nitriles 34 and amino amides 35 are used as starting material for this synthesis.…”

“…Recently, several method have been developed where azalactones 32 , 2-aryl-1, 1-dibromoethanes 33 , nitriles 34 and amino amides 35 are used as starting material for this synthesis. However, many of the synthesis protocols reported so far suffer from disadvantages such as needing anhydrous conditions 29 , use of organic solvents [29][30][31][32][33][34][35] , harsh reaction conditions 29 , prolonged reaction time 31 , use of metals and expensive reagents 29 etc., Therefore the development of an alternative cost effective, safe and environment friendly reagent system is attractive. In continuation of our earlier interest in synthesizing variety of organic molecules of industrial and pharmacological interest, we attempted and succeeded to synthesize a series of imidazolidine derivatives catalyzed by activated fly ash under microwave irradiation (MWI).…”

Copper-incorporated fluorapatite encapsulated iron oxide nanocatalyst for synthesis of benzimidazoles

“…Three years later, Ladenburg procured the identical compound by refluxing 3,4-diaminotoluene with acetic acid [11]. Various methodologies have been used for the synthesis of benzimidazole derivatives, which include conversion of esters using an aluminum reagent [12], the oxidative cyclodehydrogenation of Schiff bases, which is generated from o-phenylenediamine and aldehydes in the presence of several catalysts [13], such as cabalt(II) chloride hexahydrate [14], iodine [15], cetylpyridinium bromide [16], the condensation of o-aryldiamines and aldehyde in refluxing nitrobenzene [17], direct condensation of o-aryldiamines and carboxylic acids [18,19] or their derivatives [20] in the presence of catalysts, such as polyphosphoric acid [21], ionic liquids [22], p-TsOH [23], SiO 2 as solid support [24], microwave irradiation using polyphosphoric acid [25], and intramolecular N-arylations of amidines mediated by potassium hydroxide [26]. Although these reported approaches are significant, but some of them have drawbacks like strict reaction conditions, prolonged reaction period, low yield, expensive catalysts, non-recoverability of the catalysts, use of toxic solvents, and co-occurrence of several side reactions.…”

Expeditious and Efficient Synthesis of Benzoxazoles, Benzothiazoles, Benzimidazoles Catalyzed by Ga(OTf)3 under Solvent‐Free Conditions

“…12 It is therefore not surprising that many synthetic methods have been reported for the preparation of these compounds. A wide range of methods have been developed for the synthesis of these heterocycles which include the reaction between N-ethoxycarbonylthioamides with 1,2-diamines, 13 conversion of esters using an aluminum reagent, 14 condensation of an appropriate 1,2-phenylenediamine with carboxylic acid and its derivative, 15 nitriles, 16 17c,17e,17l Due to the importance of these compounds as intermediates in organic synthesis, the development of convenient, environmental benign, high-yielding and clean approaches is highly desirable.…”