Search results for "ANRORC"

An ANRORC approach to the synthesis of perfluoroalkylated 1,2,4-triazole-carboxamides

2009

A series of perfluoroalkyl-1,2,4-triazole-carboxamides has been obtained through an ANRORClike rearrangement (Addition of Nucleophile, Ring-Opening and Ring-Closure) of 5- perfluoroalkyl-1,2,4-oxadiazole-3-carboxamides with methylhydrazine or hydrazine. The initial addition of the bidentate nucleophile to the electrophilic C(5) of the 1,2,4-oxadiazole ring, followed by ring opening and ring closure, leads to the formation of triazoles in good yield under mild experimental conditions. In some cases, a competitive ANRORC-enlargement reaction to form 1,2,4-triazin-6-ones was also observed. Obtained carboxamidotriazoles have also been explored as precursors for the synthesis of 3(5)-perfluoroal…

Synthesis of Fluorinated Indazoles Through ANRORC-Like Rearrangement of 1,2,4-Oxadiazoles with Hydrazine.

2006

A series of 6-substituted fluorinated indazoles has been obtained through an ANRORC-like rearrangement (Addition of Nucleophile, Ring-Opening and Ring-Closure) of 5-tetrafluorophenyl-1,2,4-oxadiazoles with hydrazine. The initial addition of the bidentate nucleophile to the electrophilic C(5) of the 1,2,4-oxadiazole ring, followed by ring opening and ring closure, leads to the formation of fluorinated indazoles in high yield under mild experimental conditions. Functionalization of the C(6) in the final indazole nucleus was preliminarily achieved through a nucleophilic aromatic substitution on the starting 5-pentafluorophenyl-1,2,4-oxadiazole.

Synthesis of fluorinated 1,2,4-oxadiazin-6-ones through ANRORC rearrangement of 1,2,4-oxadiazoles

2009

Abstract The reaction of 3-ethoxycarbonyl-5-perfluoroalkyl-1,2,4-oxadiazoles with hydroxylamines has been investigated, evidencing the possibility of competitive reaction paths. Nucleophilic addition of hydroxylamine to the electrophilic C(5) of the 1,2,4-oxadiazole ring, followed by ring-opening and ring-closure with enlargement, leads to high yield and in very mild experimental conditions to the formation of 5-hydroxyamino-3-perfluoroalkyl-6 H -1,2,4-oxadiazin-6-ones, one of these presenting water gelation ability. In turn, reactions with N -methylhydroxylamine lead the exclusive formation of 4-perfluoroacylamino-2-methyl-2 H -1,2,5-oxadiazol-3-ones through the well known Boulton–Katritzk…

Novel ANRORC rearrangements of 1,2,4-oxadiazoles

2010

Tandem Reactions of 1,2,4-Oxadiazoles with Allylamines

2011

A reaction of 3-chloro-1,2,4-oxadiazoles with allylamine and diallylamine has been investigated. 3,3a,4,5-Tetrahydroisoxazolo[3,4-d]pyrimidines are produced through a tandem ANRORC/[3 + 2]cycloaddition pathway consisting of the addition of allylamine to the 1,2,4-oxadiazole, followed by ring opening, nitrone formation, and finally cycloaddition. 3-N-Allylamino-1,2,4-oxadiazoles were also obtained as minor products through a classical SNAr. Conversely, a reaction with diallylamine produces 3-N,N-diallylamino-1,2,4-oxadiazole and imidazoline through tandem SNAr/aziridination and nucleophilic ring opening.

Rearrangements of 1,2,4-Oxadiazole: “One Ring to Rule Them All”

2017

[Figure not available: see fulltext.] 1,2,4-Oxadiazoles are heterocycles characterized by low aromaticity and the presence of a weak O–N bond and are widely studied due to their tendency to rearrange into more stable heterocyclic compounds. This review covers literature from the last fifteen years, highlighting the general features of 1,2,4-oxadiazoles and their applications. Regarding the reactivity, the development of classical reactions (thermal and photochemical rearrangements) is presented in terms of synthetic utility and mechanistic insight. Among the relevant rearrangement reactions, the Boulton–Katritzky Rearrangement (BKR), Migration – Nucleophilic Attack – Cyclization (MN…