Recent extensions of the Morita-Baylis-Hillman reaction.

Significant progress in the development of the Morita-Baylis-Hillman (MBH) reaction has been made in the past decade. Many new variations of the MBH reaction have been well exploited, affording unexpected products and novel cyclized adducts in some cases, known as "abnormal MBH reactions". The formation of abnormal MBH adducts depends on the nature of the substrates and the employed catalytic system. This article will summarize recent advances in and mechanistic insights into such "abnormal" MBH reactions, including double-MBH reactions, sila-MBH reactions, abnormal aza-MBH reactions and tandem MBH pathways.