The protection of aminophenyl groups in organometallic syntheses

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Abstract
The trimethylsilyl group can be used to protect aminophenyl groups in organometallic transformations as follows: p-Li·C6H4·N(SiMe3)2, prepared from p-Br·C6H4·N(SiMe3)2 and lithium or n-butyl-lithium, couples normally with halogeno-silanes and -germanes and with carbonyl compounds. The intermediates can be isolated, [p-R3M·C6H4·N(SiMe3)2 : R3M = Me3Si or Et3Ge] and methanolysed, or hydrolysed directly to the free amines [p-R3M·C6H4·NH2; p-NH2·C6H4·C(OH)PhR′: R′= H or Ph]. A Wurtz–Fittig coupling reaction between m-Cl·C6H4N(SiMe3)2 and Me3SiCl gave m-Me3Si·C6H4·N(SiMe3)2 which on solvolysis afforded m-Me3Si·C6H4·NH2.