Highly Regioselective Remote Lithiation of Functionalized 1,3‐bis‐Silylated Arenes

Lithiation at the para position: The regiospecific remote lithiation of easily prepared o,o′‐bis(triethylsilyl)arenes and heteroarenes using nBuLi⋅PMDTA [PMDTA=MeN(CH₂CH₂NMe₂)₂] is reported. These lithiated (hetero)arenes react with a broad range of electrophiles to give silyl‐free tetrasubstituted products after further functionalizations.

Abstract

Substituted arenes flanked by two bulky triethylsilyl groups were regiospecifically lithiated at the 5‐position with nBuLi⋅PMDTA at 25 °C. The resulting aryllithiums reacted with a broad range of electrophiles such as ketones, isocyanates, Weinreb amides, allyl bromides, and CO₂ at 25 °C. These bis‐silylated arenes were then converted in simple reaction sequences into silyl‐free tetrasubstituted arenes. This remote lithiation was extended to 2,6‐bis(triethylsilyl)pyridine as well as 3,3′‐bis(triethylsilyl)biphenyl.

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