Piperidines from acid-catalysed cyclisations: Pitfalls, solutions and a new ring contraction to pyrrolidines. Issue 38 (20th September 2017)

• Record Type: Journal Article
• Authors: Aldmairi, Abdul H.; Griffiths-Jones, Charlotte; Dupauw, Alexis; Henderson, Laura; Knight, David W.
• Is Part Of: Tetrahedron letters. Volume 58:Issue 38(2017)
• Page Start: 3690
• Page End: 3694
• Publication Date: 2017-09-20
• Subjects: Piperidines -- Intramolecular -- Acid-catalysed -- Cyclisation -- Ring contraction; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2017.07.058
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: A new approach to piperidines by acid-catalysed cyclisation of amine derivatives. Determination of suitable N -protecting groups which lead to acid-stable piperidines. A novel ring contraction of N -sulfonyl piperidines to give pyrrolidines. Derivation of the likely mechanism of the ring contraction. Abstract: The success of acid-catalysed cyclisations of alka-4-enylamine derivatives to piperidines depends very much on the nature of the amine protecting group: while carbamates and related amides can usually be readily and cleanly transformed, the corresponding sulfonamides react further by ring contraction leading to pyrrolidines, especially when such substrates are sterically crowded.