Premium
Gold‐Catalyzed, Intramolecular, Oxygen‐Transfer Reactions of 2‐Alkynyl‐1,5‐diketones or 2‐Alkynyl‐5‐ketoesters: Scope, Expansion, and Mechanistic Investigations on a New [4+2] Cycloaddition
Author(s) -
Liu LePing,
Malhotra Deepika,
Jin Zhuang,
Paton Robert S.,
Houk K. N.,
Hammond Gerald B.
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201101448
Subject(s) - cycloisomerization , intramolecular force , cycloaddition , chemistry , catalysis , photochemistry , medicinal chemistry , organic chemistry
The gold‐catalyzed intramolecular oxygen‐transfer reactions of 2‐alkynyl‐1,5‐diketones or 2‐alkynyl‐5‐ketoesters—obtained from tetra‐ n ‐butylammonium fluoride mediated Michael addition of activated allenes to electron‐deficient olefins—furnished cyclopentenyl ketones under very mild conditions. These reactions proceeded much easier and faster than similar reactions reported in literature, and the corresponding products were obtained in very good yields. Mechanistic investigations on the cycloisomerization were carried out by means of both 18 O isotopic experiments and quantum chemical calculations. The results from both, the designed isotopic experiments and theoretical calculations, satisfactorily supported the novel proposed intramolecular [4+2] cycloaddition of a gold‐containing furanium intermediate to a carbonyl group, instead of the previous well‐accepted [2+2] pathway.