The fixation of bis(2-pyridylimino)isoindolato (BPI) ligands to dendritic carbosilanes

Abstract

Bis(2-pyridylimino)isoindolato (BPI) ligands, containing an alkynyl linker unit which allows their fixation to carbosilane dendrimers and dendrons, were synthesized by reaction of 4-nitrophthalodinitrile with 4-butynol giving the phthalodinitrile derivative 1 containing the linker. These were subsequently reacted with two molar equivalents of 2-amino-4-methylpyridine and 2-amino-4-^tbutylpyridine yielding the respective BPI protioligands 2a and 2b. Lithiation with LDA and reaction with Si–Cl or Si–OTf (OTf = triflate) end groups in core or peripheral positions of dendritic carbosilanes gave the endodendrally and expdendrally functionalized dendrimers. Among these the first and second generation dendrimers [G-1]_8-exo-4-[CCCH₂CH₂O]-10-MeBPI (8), [G-1]_12-exo-4-[CCCH₂CH₂O]-10-MeBPI (9) and [G-2]_16-exo-4-[CCCH₂CH₂O]-10-MeBPI (10) were synthesized and fully characterized. The functional dendrimers were metallated by reaction with [(PhCN)₂PdCl₂] in dichloromethane to give the corresponding pallada-dendrimers.