Benzylic Grignard reagents: application of [Mg(anthracene)(thf)3](thf = tetrahydrofuran) in regioselective Grignard formation and C–O cleavage in benzyl ethers

Abstract

Benzylic Grignard reagents (2)–(4), bearing ortho- and para-halogeno ring substituents, are readily accessible by treating the corresponding benzylic halide with [Mg(anthracene)(thf)₃](1) in tetrahydrofuran (thf); o- and p-chloromethyl(methoxymethyl)benzenes with (1) rapidly yield ‘di-Grignards’ whereas the meta-isomer only affords a mono-Grignard' (5), and bis(methoxymethyl)benzenes slowly undergo C–O cleavage, (6).