Abstract
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.