Facile One‐Pot Synthesis of Polysubstituted Pyridinium Salts by Annulation of Enamines with Alkynes. Issue 22 (10th March 2023)

• Record Type: Journal Article
• Authors: Lee, Seokwoo; Yoo, Hanbin; Park, Soojun; Yoon, Ran; Kim, Sanghee
• Is Part Of: Chemistry. Volume 29:Issue 22(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-03-10
• Subjects: 6-endo cyclization -- heterocycles -- one pot -- propargyl enamine -- pyridinium; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202300059
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: An efficient and facile synthesis of highly substituted pyridinium salts through the annulation of enamines with alkynes is reported herein. A Ag2 CO3 /HNTf2 synergistically acting catalyst system was developed and used in a condensation reaction between carbonyl substrates and propargylamine to afford structurally diverse pyridinium salts. A mechanistic investigation shows that this one‐pot transformation proceeded via selective 6‐ endo ‐ dig cyclization of the in situ generated propargylenamine and protonolysis of the resulting vinyl–silver intermediate. The reaction conditions are mild, and the substrate scope is broad. During the cyclization, an unusual inversion of the normal reactivity of α, β‐unsaturated carbonyl systems was observed. Abstract : An efficient and facile synthesis of highly substituted pyridinium salts through annulation of enamines with alkynes is reported. The keys to this advancement are: 1) one‐pot, mild reaction conditions; 2) broad substrate scope; and 3) selective 6‐ endo ‐ dig cyclization.