Diversity‐oriented Multicomponent Heterocyclizations Involving Derivatives of 3(5)‐Aminoisoxazole, Aldehydes and Meldrum's or N,N′‐Dimethylbarbituric Acid

Abstract

5‐Amino‐3‐methylisoxazole and 3‐amino‐5‐methylisoxazole were studied in details in the multicomponent heterocyclizations with aromatic aldehydes and Meldrum's or N,N′‐dimethylbarbituric acid with help of classical and non‐classical (microwave and ultrasonic irradiation) activation methods.

New tricks of well-known aminoazoles in isocyanide-based multicomponent reactions and antibacterial activity of the compounds synthesized

“…Therefore, the first type of aminoazoles studied in our work was 5-amino- N -aryl-1 H -pyrazole-4-carboxamide that showed 1,3-binucleophile properties in the condensation with aromatic aldehydes and alkylisocyanides giving the product resulting from GBB-3CR. On the other hand, 3-amino-5-methylisoxazole in MCRs often acted as primary amine [ 102 – 106 ], that was confirmed in our case by treatment with aromatic aldehydes, alkylisocyanides and phenylpropiolic acid resulting in the corresponding products of the Ugi-4CR ( Scheme 2 ).…”

A review of the synthetic strategies toward spirobarbiturate-fused 3- to 7-membered rings

“…This journal is © The Royal Society of Chemistry 2022 proceed when using the isomeric form of 90 (3-amino-5methylisoxazole), and instead of heterocyclization, a barbiturate-based olefin was obtained. 94 More recently, the catalytic versatility of L-proline has been applied to a one-pot L-prolinecatalyzed domino aza-Diels-Alder reaction involving 3-amino crotanonitrile 91, hydroxylamine hydrochloride, aromatic aldehydes, and 1,3-dimethyl barbituric acids in water under reflux, allowing the corresponding functionalized spirobarbituratefused isoxazolo [5,4-b]pyridine to be obtained in satisfactory yield under mild reaction conditions. The best reaction conditions for performing this one-pot multi-component aza-Diels-Alder reaction involved using a catalytic amount of L-proline to synthesize 5-amino-3-methylisoxazole 90, which further condensed with aromatic aldehydes for the in situ formation of the imine intermediate as a diene.…”

Mechanisms and Origins of Regio- and Stereoselectivities in NHC-Catalyzed [3 + 3] Annulation of α-Bromoenals and 5-Aminoisoxazoles: A DFT Study

“…In this context, the search for effective synthesis methods for functionalized heterocycles incorporating 5-aminoisoxazole motifs has received widespread attention. For example, dihydroisoxazolo­[5,4- b ]­pyridin-6-ones have been synthesized through a multicomponent reaction involving Meldrum’s acid, 5-amino-isooxazole, and aldehydes . Several works on other synthesis methods have also been reported .…”