MgI(2)-mediated ring expansions of secondary methylenecyclopropyl amides.
Ring expansion of secondary methylenecyclopropyl amides in the presence of MgI2 was investigated. Various isomeric five-membered unsaturated lactams were obtained, depending on the character of the substituent Q. The amide group served as a nucleophile in ring closing as well as an activator for ring opening. In the presence of a variety of aryl aldimines or aldehydes, alkylative ring expansion occurred in a single step under mild and neutral conditions leading to gamma'-amino- or -hydroxy-alkylated pyrrol-2-ones. Also, it was shown that a 4-methylpyrrol-2-one could be transformed to a gamma-hydroxy-alkylated product by the use of a direct vinylogous aldol reaction.
Lautens
Mark
M
Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George St., Toronto, Ontario, Canada M5S 3H6. mlautens@chem.utoronto.ca
Han
Wooseok
W
Liu
Jack Hung-Chang
JH