Photochemical Rearrangement of <i>N</i>-Mesyloxylactams: Stereospecific Formation of <i>N</i>-Heterocycles
作者:Alexandre Drouin、Dana K. Winter、Simon Pichette、Samuel Aubert-Nicol、Jean Lessard、Claude Spino
DOI:10.1021/jo101805q
日期:2011.1.7
N-Mesyloxylactams undergo an efficient ring-contraction to N-heterocycles of various ring sizes. Yields increase with the degree of substitution α to the carbonyl. The stereochemical information of a chiral migrating carbon is conserved making this reaction a synthetically useful complement to the well-known Hofmann, Curtius, Lossen, and Schmidt rearrangements.
can undergo a thermal ring contraction after an in situ triflation. High yields of ring-contraction products are obtained with DBU when the migrating carbon is a methylene, while best results are obtained with Et3N for the migration of quaternary carbons. In some cases, the regiochemical outcome of the reaction can be controlled by changing the base. This novel thermalrearrangement complements a similar