Stabilization of reactive aldehydes by complexation with methylaluminum bis(2,6-diphenylphenoxide) and their synthetic application

Article abstract of DOI:10.1021/ja00063a013

Reactive aldehydes such as formaldehyde and α-chloro aldehydes can be successfully generated by treatment of readily available trioxane and α-chloro aldehyde trimers, respectively, with methylaluminum bis(2,6-diphenylphenoxide) (MAPH), and stabilized as their 1:1 coordination complexes with MAPH. The resulting CH₂=O·MAPH complex reacts with a variety of olefins to furnish ene-reaction products with excellent regio- and stereoselectivities. In addition, this complex as well as α-chloro aldehyde-M APH complexes can be utilized as a stable source of gaseous formaldehyde and reactive α-chloro aldehydes, respectively, for the nucleophilic addition of various carbanions (organometallics, enolates, etc.). Formation of reactive aldehyde-MAPH complexes is firmly confirmed by ¹H NMR spectroscopy. A space-filling model of aldehyde-M APH complexes implies that formaldehyde and α-chloro aldehydes coordinated with MAPH may be electronically stabilized by two parallel phenyl groups of aluminum ligands.