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.
A nucleophilic addition/ring-contractive rearrangement of α-bromo N-alkoxylactams with organometallic reagents was developed, providing an efficient access to α-acylpyrrolidines incorporating various C(sp2) units such as aryl, heteroaryl, and alkenyl groups. The sequential reaction proceeds through a five-membered chelate formation using nucleophilic addition followed by ring contraction via the formation