Coinage Metals-Catalyzed Cascade Reactions of Aryl Alkynylaziridines: Silver(I)-Single vs Gold(I)-Double Cyclizations

• Published in: Journal of organic chemistry 2012-05, Vol.77 (9), p.4323-4341
• Main Authors: Kern, Nicolas, Blanc, Aurélien, Miaskiewicz, Solène, Robinette, Michelle, Weibel, Jean-Marc, Pale, Patrick
• Format: Article
• Language: English
• Subjects: Chemical reactivity; Chemistry; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives; Heterocyclic compounds with only one n hetero atom and condensed derivatives; Kinetics and mechanisms; Organic chemistry; Preparations and properties; Reactivity and mechanisms
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo300294r

Alkynylaziridines carrying an aryl group could be efficiently converted into aminoallenylidene isochromans, isoquinolines, or tetrahydronaphtalenes with silver(I) salts and into 1-azaspiro[4.5]decane derivatives with gold(I) complexes. Mechanistic investigations revealed that both Ag- and Au-catalyzed reactions involved a Friedel–Crafts type intramolecular reaction leading to an allene and that Au also rapidly promoted a second intramolecular cyclization of the aminoallene intermediate to the corresponding spiro derivative. Stereochemical investigations suggested an anti-SN2′-type pathway for the first cyclization leading to a stereodefined allene, which could then be cyclized to the corresponding stereodefined spiro product. These results highlight the duality between oxo- or azaphilicity and alkynophilicity of Ag and Au as well as their complementarity in terms of reactivity.