1998 ring closure reactions

ring closure reactionsO 0130

05 - 042Ring Expansions of N-Methyl-1,2,5-oxadiazolium and 1,2,3-Triazolium Perchlorate Salts with Bases to Six-Membered Azines:Direct Detection of an Addition Intermediate in an Addition–Elimination Mechanism and a Degradation of 1,2,5-OxadiazoliumSalts to α-Cyano Nitrones. — Reactions of triazolium and oxadiazoliumperchlorate salts (I) and (V), resp., with various bases give ring expansionsto substituted triazines (II) or oxadiazines (VI). With cyanide as base, thereactions follow an addition–elimination pathway. When oxadiazolium salts aretreated with KCN, ring degradation to α-cyano-nitrones (VII) competes withring expansion. — (BUTLER, R. N.; MCKENNA, E. C.; MCMAHON, J. M.;DALY, K. M.; CUNNINGHAM, D.; MCARDLE, P.; J. Chem. Soc., PerkinTrans. 1 [old] (1997) 19, 2919-2923; Chem. Dep., Univ. Coll., Galway, Ire.; EN)

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1998 ring closure reactions

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