Ammonium Niobium Oxalate (ANO)

Ammonium niobium oxalate (ANO) as an efficient catalyst in the Paal–Knorr synthesis of N-substituted pyrroles

“…Based on the results of the studies in the reaction optimization and on our early studies reporting the reactivity of ANO as a Lewis acid catalyst, 45–50 we propose a plausible reaction mechanism for the transformation, through a hemiaminal reaction pathway. Initially, a Lewis acid–base complexation between a non-bonding oxygen lone pair from hexan-2,5-dione 1 and the niobium coordination sphere occurs, to give the strong electrophilic complex I .…”

“…The two most widely studied Nb-based catalysts are niobium pentachloride (NbCl 5 ) and niobium pentoxide (Nb 2 O 5 ). [41][42][43][44][45][46] 47 Considering its fabulous properties, since 2015 we have been devoting our efforts to the development of reaction models employing ANO as a catalyst, exploring the synthesis of N-based heterocycles and aiming to expand the scope of application of this salt (Scheme 1, our advances employing ANO as a catalyst). [48][49][50] Thus, considering our recent efforts in the development of ecofriendly synthetic protocols using ANO as a catalyst, we have disclosed herein an efficient approach to access N-substituted pyrroles through an ANO-catalyzed Paal-Knorr reaction.…”

“…Besides, ANO is a very cheap, bench stable and easy to handle Nb-based species, which presents a very low toxicity and no air- or moisture sensitivity. 47 Considering its fabulous properties, since 2015 we have been devoting our efforts to the development of reaction models employing ANO as a catalyst, exploring the synthesis of N-based heterocycles and aiming to expand the scope of application of this salt (Scheme 1, our advances employing ANO as a catalyst). 48–50…”

Fabrication of conductive Nb-doped anatase TiO2 thin films by mist chemical vapor deposition using aqueous solutions of water-soluble Ti and Nb compounds

“…22,25) Ammonium niobium oxalate (ANO), NH 4 [NbO(C 2 O 4 ) 2 (H 2 O) 2 ], is known to be water-soluble. 26) These water-soluble compounds could be viable for the deposition of TNO films through aqueous solution-based methods.…”