Ring Strain‐Promoted Activation of Pyridines by a Saturated BSi ₂ Cycle

Ring strain is a well‐established strategy to increase reactivity. Employing an elusive saturated BSi 2 ring motif, we here exploit the size mismatch between boron and silicon to this end. The reaction of disilenide Tip 2 Si = SiTipLi with BH 3 ·SMe 2 selectively affords the lithium salt of anionic boratadisilirane c ‐SiTip 2 SiHTipBH 2 − (Tip = 2,4,6‐triisopropylphenyl), which according to DFT calculations on the parent system BSi 2 H 6 − is much more strained than isoelectronic analogues such as cyclopropane (C 3 H 6 ), boratirane (BC 2 H 6 − ), and cyclotrisilane (Si 3 H 6 ). Indeed, it spontaneously and selectively activates a range of pyridine derivatives: pyridine itself undergoes ortho ‐CH activation under dearomatization of a second equivalent; 2 equivalents of para ‐dimethylaminopyridine (DMAP) are C─C‐coupled in ortho ‐ and meta ‐position; and pentafluoropyridine (PFP) is CF‐activated in para ‐position.