Palladium-catalysed methylation of aryl halides in ionic liquids with stabilized AlMe3

A new protocol for the methylation of aryl halides using the AlMe3 analogue DABAL-Me3 in a VOC/IL biphasic system is described. Very good isolated yields and chemoselectivities (methylation vs homocoupling), were observed in alkylmethylimidazolium and DABCO-based ILs, in presence of a bulky substituted phosphine (XPhos) and the structurally related sulfonated phosphine (XPhosSO3H). Recycling experiments of the IL-catalyst systems were satisfactory only in case of the butyldimethylimidazolium IL due to catalyst loss to the VOC phase.

Methylation of aryl halides with DABAL-Me3 in a VOC/IL system is proposed. Good yields and high chemoselectivity were observed. Satisfactory recycling of catalytic phase was attained using a charged phosphine ligand.Figure optionsDownload high-quality image (46 K)Download as PowerPoint slide