Studies with 2‐arylhydrazononitriles: Further investigations on reactivity of 2‐arylhydrazononitriles towards hydroxylamine

Abstract

The utilization of arylhydrazononitriles (6‐9) for synthesis of azoles is demonstrated. Thus, arylazomalononitriles (6) reacted with hydroxylamine hydrochloride to afford isoxazol‐5‐imine (10), amidoxime (12) and bis‐amidoxime (13) derivatives depending upon both the reaction conditions and molar ratio employed. 2‐Thiazolyl‐2‐arylhydrazononitriles (7) and cyanoformazans (8) gave 1,2,3‐triazole derivatives (15) and (17) respectively upon treatment with hydroxylamine hydrochloride and concomitant loss of water molecule. Formation of novel 1,2,4‐triazin‐5(4H)‐one derivatives (21) has efficiently been carried out by treatment of amidoximes (18) with acetic anhydride in acetic acid.

Studies with Azinylacetonitriles: 2-Pyridylacetonitrile as a Precursor to Functionally Substituted Pyridines

“…It is well accepted that the methylene moieties in heteroaromatic substituted acetonitriles are reactive toward electrophiles under mild conditions [ 1 , 2 , 3 ]. This reactivity has been utilized for synthesis of a variety of functionally substituted azoles [ 4 , 5 ] and condensed azoles [ 6 , 7 ]. However, little has been reported on the utility of azinylacetonitriles for synthesis of functionally substituted azines [ 8 ].…”

Chemistry of 1,2,3-triazoles

“…Another transformation of bis(hydrazones), hydrazonoamidoximes, and hydrazonohydrazides yielding 2-aryl-1,2,3-triazoles usually occurs under condensation conditions and is accomplished by the elimination of a leaving group [240,[275][276][277][278][279][280][281][282][283][284][285][286][287][288][289][290][291][292][293][294].…”

“…Arylhydrazonoacetamidoximes are widely accessible and can be easily transformed into 5-amino-1,2,3-triazoles by heating in DMF, EtOH with sodium acetate, EtONa, or piperidine, followed by treatment with POCl 3 , or by reflux in acetic anhydride, under microwave activation [275][276][277][278][279][280][281]. Refluxing hydrazones 219 with acetic anhydride causes the cyclization, which usually leads to mono-or diacetylated dehydration products (Scheme 77) [277][278][279].…”

“…There is also considerable interest in designing molecules that are able to mimic the carbohydrate units and evaluating them against glucosidase enzymes [278]. The combination of both carbohydrate and 1,2,3-triazole structural units has proven to be useful for the production of new compounds with various biological activities [ [279][280][281][282]. One of the first examples of this approach was the synthesis [283] of glycosyl triazoles (162a,b) at the anomeric position followed by inhibitory evaluation against Escherichia coli galactosidase (ECG) and bovine liver galactosidase (BLG).…”

Studies on 2-Arylhydrazononitriles: Synthesis of 3-Aryl-2-arylhydrazopropanenitriles and Their Utility as Precursors to 2-Substituted Indoles, 2-Substituted-1,2,3-Triazoles, and 1-Substituted Pyrazolo[4,3-d]pyrimidines

“…2-Arylhydrazononitriles 4a , b are versatile reagents and their chemistry has recently attracted considerable interest [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. In previous recent work we have established the utility of these compounds as precursors for 1,2,4-triazoles [ 5 ], 1,2,3-triazoles [ 6 ], and pyrazolo[1,5- a ]pyrimidines [ 7 , 8 ]. In conjunction to that work we report herein an easy route to the title compounds and their utility as precursors for synthesis of various heterocycles.…”