Fluorinated heterocyclic compounds. The first example of an irreversible ring-degenerate rearrangement on five-membered heterocycles by attack of an external bidentate nucleophile

Ivana Pibiri, Nicolo' Vivona, Andrea Pace, Silvestre Buscemi, Camilla Zaira Lanza, Domenico Spinelli

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)

Abstract

The reactions of 5-perfluoroalkyl-1,2,4-oxadiazoles 3 with hydroxylamine in DMF give the regioisomeric 3-perfluoroalkyl-1,2,4-oxadiazoles 4 in excellent yields. This process is thefirst example of ring-degenerate rearrangement (RDR) occurring on five-membered heterocycles by attack of an external bidentate nucleophile, which replaces two heteroatoms of the ring. We suggest that an ANRORC-like mechanism occurs in which the addition of the nucleophilic nitrogen atom (NH2OH) on the C(5) atom of 3 is followed by ring opening and irreversible ring-degenerate closure by attack of the nucleophilic oxygen atom (=NOH) on the C(3) atom of the originalring, realizing an elegant and efficient synthesis of 4 by a C(3)−C(5) annular switch. Ab initio computations on the starting materials and final products, as well as on the proposedintermediates, support the mechanism and shed light on the features of the reaction.
Original languageEnglish
Pages (from-to)974-980
Number of pages7
JournalEuropean Journal of Organic Chemistry
Publication statusPublished - 2004

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry

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