Synthesis, oxidation and dehydrogenation of cyclic N,O‐ and N,S‐acetals. Part III. Transformation of N,O‐acetals: 3‐acyl‐1,3,4‐oxadiazolines

Abstract

Various aldehyde and ketone acylhydrazones are synthesized and, under acylating conditions, cyclized into 3‐acyl‐1,3,4‐oxadiazolines. The scope and limitations of these cyclizations and the possible side reactions (e.g. formation of the open‐chain N,O‐acylhydrazinocarbinols) are dissected. For the first time, simple, convenient and efficient dehydrogenations of 3‐acyl‐1,3,4‐oxadiazolines to oxadiazoles by treatment with potassium permanganate, or more conveniently, with ammonium cerium(IV) nitrate (CAN) are presented. CAN oxidation of 2,2‐disubstituted 3‐acyl‐1,3,4‐oxadiazolines, as well as that of aldehyde diacylhydrazones (open‐chain isomers of 2,5‐disubstituted 3‐acyl‐1,3,4‐oxadiazolines) regenerates the parent carbonyl compounds.

Advances in Synthetic Applications of Hypervalent Iodine Compounds

“…Similar hypervalent iodine-induced heterocyclizations of the appropriate amide or amine precursors have been utilized in several important synthetic transformations, such as DIB-promoted preparation of aminoindolines by inter- or intramolecular oxidative deamination of terminal alkenes and amines, preparation of 1-arylcarbazoles by metal-free electrocyclization, preparation of highly substituted pyrrolin-4-ones by BTI-promoted cyclization of enaminones, preparation of 2-substituted-4-bromopyrrolidines by DIB-promoted oxidative bromocyclization of homoallylic sulfonamides, synthesis of 1,2,4-thiadiazoles by the reaction of [bis­(acyloxy)­iodo]­benzenes with 1-substituted thioureas, , DIB-promoted synthesis of pyrazolo- and isoxazolopyrimidines, preparation of azaspirocycles by the BTI-promoted nitrenium ion cyclizations, − synthesis of lactams and spiro-fused lactams by the reaction of N -acylaminophthalimides with BTI, preparation of various substituted 1,2,4-triazolo­[4,3- a ]­pyrimidines by the DIB-induced oxidation of 2,4-pyrimidinylhydrazones, − preparation of pyrrolidino[60]­fullerene from the DIB-induced reaction of C 60 with amino acid esters, preparation of 1,3,4-oxadiazoles from acylhydrazones by BTI-mediated oxidations, − preparation of substituted 1,2,4-triazolo­[4,3- a ]­quinoxalines from arenecarboxaldehyde-3-methyl-2-quinoxalinylhydrazones, , preparation of N -substituted indoles by BTI-induced cyclization of enamines, the DIB-mediated preparation of indoles from N -aryl enamines, the DIB- or BTI-mediated synthesis of oxindoles and spirooxindoles, , the BTI-mediated synthesis of carbazolones and 3-acetylindoles, preparation of polysubstituted pyrroles from 3-alkynyl amines with DIB, the one-pot synthesis of substituted pyrroles using DIB, and the synthesis of 2-arylproline derivatives by intramolecular oxyamination of alkenes with BTI or DIB …”

The synthesis and biological activities of 3-acyl- 2,3-dihydro-1,3,4-oxadiazole/ 3-acyl-1,3,4-oxadiazoline derivatives obtained from hydrazide-hydrazones

“…The monoamine oxidase inhibitory activities of 3-acetyl-1,3,4-oxadiazolines were investigated by Maccioni and co-workers (47). The most detailed researches have been made by Somogyi and co-workers (42,(48)(49)(50)(51).…”

“…The dehydrogenation of 3-acetyl-2,3-dihydro-1,3,4-oxadiazoles 24 with potassium permanganate has been given substituted 1,3,4-oxadiazoles 25 (51) Other acyl derivatives The intramoleculer cyclization of hydrazide hydrazones have also been carried out with propionic anhydride 31 (40), benzoyl chloride 32 (48), 33 (63) and substituted isocyanates 35, 36 (71,72).…”

Planejamento, síntese e avaliação da atividade anti-T. cruzi de derivados furfurilidênicos com estruturas azometínica e oxadiazolínica

“…Para obtenção dos compostos furfurilidênicos azometínicos, 4a -j da série I, figura 16, ocorre a reação de condensação entre a benzidrazida, 3a -j, e o diacetato de 5-nitro-2-furfuraldeído com pureza de 98% (Sigma -Aldrich Chemical Company, Inc) (CAREY, SUNDBERG, 2000, SOLOMONS, FRYHLE, 2004, MARCH, 2001 , MACCIONI et al, 2011, ALMEIDA, 2009, LI, MA, CAO, 2009, SOMOGYI, 2007, ROLLAS, GULERMAN, ERDENIZ, 2002.…”

“…Para a análise de PCA, na matriz de dados, a atividade biológica foi considerada como variável dependente. Os dados foram decompostos em duas matrizes, uma de escores, relacionando as amostras, e outra de pesos (loadings), relacionando as variáveis (MONTANARI, 2011, BEEBE, PELL, SEASHOLTZ, 1998 , MACCIONI et al, 2011, ALMEIDA, 2009, LI, MA, CAO, 2009, SOMOGYI, 2007, JOULE, MILLS, 2007, ROLLAS, GULERMAN, ERDENIZ, 2002.…”