Recent advances in organocatalytic asymmetric morita-baylis-hillman/aza- morita-baylis-hillman reactions

摘要

The latest issue of Chemical Reviews focused on the advancements in asymmetric Morita-Baylis-Hillman (MBH)/aza-MBH reactions from 2009 to 2011. Several researchers conducted kinetic and theoretical studies on the MBH mechanism, while others performed an extensive theoretical study, which supported their own kinetic observations and those of McQuade about the proton transfer step. Two distinct pathways leading to the products were proposed, including a second molecule of aldehyde participates the reaction to form a hemiacetal alkoxide hemi1 followed by rate-limiting proton transfer as proposed by McQuade. Some other researchers presented a detailed computational and experimental reinvestigation on the amine-catalyzed MBH reaction of benzaldehyde with methyl acrylate. Another team of researchers also investigated the mechanism of aza-MBH via the ESI-MS(/MS) technique and proposed a rational mechanism for the aza-MBH reaction. This team monitored the DABCO-catalyzed aza-MBH reaction of methyl acrylate 2 with imine 12 by ESI-MS(/MS) spectrometry and intercepted the key intermediates and a unique bissulfonamide intermediate.