Synthesis of the sterically encumbering terphenyl silyl and alkyl amines HN(R)ArMes2HN(R)ArMes2 (R = Me and SiMe3), their lithium derivatives LiN(R)ArMes2LiN(R)ArMes2, and the tertiary amine Me2NArMes2Me2NArMes2

Reaction of the terphenyl derivative BrMgArMes2(ArMes2=C6H3-2,6-Mes2) (synthesized in “one pot” directly from BrMgMes and 1-lithio-2,6-dichlorobenzene) with p  -toluenesulfonyl azide afforded the azide N3ArMes2(ArMes2=C6H3-2,6-Mes2) (1) in 43% yield. Treatment of 1 with LiAlH4 gave the amine H2NArMes2H2NArMes2 (2) in high yield (88%). Reaction of 2 with 1.1 equivalents of n  -BuLi afforded the lithium derivative Li(H)NArMes2Li(H)NArMes2 (3), which was quenched with excess SiMe3Cl to yield the silyl amine HN(SiMe3)ArMes2HN(SiMe3)ArMes2 (4). Reaction of 4 with n  -BuLi gave LiN(SiMe3)ArMes2LiN(SiMe3)ArMes2 (5) in 65% yield. The related secondary terphenyl methyl amine HN(Me)ArMes2HN(Me)ArMes2 (6) was synthesized by reaction of 2 with five equivalents of methyl iodide in refluxing acetonitrile. In addition, the tertiary amine Me2NArMes2Me2NArMes2 (7) was formed. Reaction of 6 with n  -BuLi in hexane solvent provided the lithium derivative [LiN(Me)ArMes2]2[LiN(Me)ArMes2]2 (8). All compounds were characterized by 1H and 13C NMR spectroscopy. Compounds 2, 4, and 6 were found to be monomeric and 8 dimeric in the solid state by X-ray crystallography. Compound 8 featured a dimeric Li2N2 core, where the Li ions are two coordinate.

Graphical abstractThe sterically encumbering terphenyl silyl and alkyl amines HN(R)Mes2HN(R)Mes2 (R = Me and SiMe3) have been synthesized from the primary amine, H2NMes2H2NMes2. Reaction of these amines with n  -BuLi afforded their lithium derivatives, LiN(R)ArMes2LiN(R)ArMes2.Figure optionsDownload full-size imageDownload as PowerPoint slide