A Lewis Acid-Promoted Michael Addition and Ring-Expansion Cascade for the Construction of Nitrogen-Containing Medium-Sized Rings

A Lewis acid-promoted annulation of azadienes and cyclobutamines was developed. This reaction proceeded through Michael addition and ring-expansion cascade, affording the corresponding nitrogen-containing medium-sized rings with a broad scope in moderate to high yields. The catalytic asymmetric version of this reaction has also been explored using a chiral base.

Automated summary

A Lewis acid-promoted annulation method for the synthesis of nitrogen-containing medium-sized rings from azadienes and cyclobutamines has been developed. This reaction involves a cascade of Michael addition and ring-expansion, giving moderate to high yields and a broad scope of products. The use of a chiral base has also been explored for the catalytic asymmetric version of this reaction.