Zirconyl Nitrate as an Efficient Catalyst for Facile Synthesis of 2-Aryl-2,3-dihydroquinolin-4(1H)-one Derivatives in Aqueous ­Medium

Abstract

A simple, green, and efficient method is introduced for the synthesis of 2-aryl-2,3-dihydroquinolin-4(1H)-ones under mild reaction conditions with improved yields by intramolecular cyclization of o-aminochalcones with zirconyl nitrate [Zn(O)(NO3)2·nH2O] as a water-tolerant Lewis-acid catalyst.

Investigating the Mechanism of the Catalytic Intramolecular Aza-Wittig Reaction Involved in the Synthesis of 2-Methylbenzothiazole from the Perspective of Bonding Evolution Theory

“…For these authors, this efficient catalytic method was the main protocol to synthesize 2-substituted benzothiazole with excellent yields. Later, Gorepatil et al 45 performed the synthesis of benzothiazoles with high yields from o-amino(thio)phenols and aldehydes using samarium triflate as catalyst. The reusable character of samarium triflate was a key parameter for the authors to choose this catalyst over heterogeneous Lewis acid catalysts commonly used for this synthesis.…”

Samarium(III) Triflate in Organic Synthesis: a Mild and Efficient Catalyst

“…[84] The same group also reported a facile methodology for the synthesis of benzothiazoles and benzoxazoles 62 from orthoaminothiophenols, ortho-aminophenols 59, and different aldehydes 60 in the presence of the samarium triflate since benzoxazoles and benzothiazoles are known to display a wide range of biological activities (Scheme 22). [28] The merit of this methodology consists of a water-tolerant, reusable Lewis acid catalyst (88-94 % recovery), green solvent, and mild reaction conditions.…”

“…Several metal triflates such as Bi(OTf) 3 , In(OTf) 3 , Yb(OTf) 3 , Er(OTf) 3 , Sc(OTf) 3 , Ce(OTf) 3 , Sm(OTf) 3 , and others play a vital role in developing novel eco-friendly protocols for organic transformations with excellent efficiency and selectivity since these reactions have been shown to be water-tolerant, and reusable Lewis acids catalysts. [24][25][26][27][28][29][30][31][32] Several traditional synthetic methodologies suffer from various demerits including vigorous reaction conditions, costly reagents, poor yields, prolonged reaction times, co-occurrence of various side reactions, and monotonous work-up. [33] Among lanthanide triflate, samarium(III) triflate (samarium(III) trifluoromethanesulfonate) has currently attracted significant attention in organic synthesis as it is known as a mild, moisture tolerant, and effective Lewis catalyst.…”

“…However, the most stable oxidation state of lanthanides is +3 since it is gained by removing the outermost 2 electrons from the 6 s‐subshell and 1 electron from the 4 f‐subshell. Several metal triflates such as Bi(OTf) 3 , In(OTf) 3 , Yb(OTf) 3 , Er(OTf) 3 , Sc(OTf) 3 , Ce(OTf) 3 , Sm(OTf) 3 , and others play a vital role in developing novel eco‐friendly protocols for organic transformations with excellent efficiency and selectivity since these reactions have been shown to be water‐tolerant, and reusable Lewis acids catalysts [24–32] …”

Samarium(III) Triflate as an Efficient and Reusable Catalyst for the Facile Synthesis of 1,2,4,5-Tetrasubstituted Imidazoles

“…In order to overcome aforesaid drawbacks, heterogeneous Lewis acids have been playing a vital role in organic synthesis due to their characteristics like ease of handling, increased reaction rate, higher selectivity, simple work-up, and most importantly, catalyst recoverability [45,46]. Our group has also been working on developing Lewis acid-based, greener approaches for synthesizing different types of heterocyclic compounds [47][48][49]. One of the popular catalyst metal triflates has widely been employed in cyclocondensation and other organic reactions [50][51][52][53][54][55][56][57][58][59][60].…”