ИСТИНА

Isonitriles (isocyanides) combine rich and diverse reactivity with an intriguing dichotomy of electronic properties [1]. In particu- lar, in radical addition to triple nitrogen-carbon bond the substrates demonstrate that they behave as stereoelectronic chameleons [2]. Unlike reactions with alkenes and alkynes, radical addition to isonitriles proceeds in 1,1-addition-manner, which means we deal here with unique non-Markovnikov case. Addition of alkyl, aryl, heteroatom-substituted and heteroatom-centered radicals reveals a number of electronic, supramolecular, and conformational effects potentially useful for the practical control of isonitrile-mediated radical cascade transformations. Addition of alkyl radicals reveals two stereoelectronic preferences. First, the radical attack aligns the incipient C•••C bond with the aromatic π-system. Second, one of the C-H/C-C bonds at the radical carbon eclipses the isonitrile N-C bond. Combination of these stereoelectronic preferences with entropic penalty explains why the least exergonic reaction (addition of the t-Bu radical) is also the fastest. Heteroatomic radicals reveal further unusual trends. In particular, the Sn radical addition to the PhNC is much faster than addi- tion of the other group IV radicals, despite forming the weakest bond. This combination of kinetic and thermodynamic properties is ideal for applications in control of radical reactivity via dynamic covalent chemistry and may be responsible for the historically broad utility of Sn-radicals (“the tyranny of tin”). In addition to polarity and low steric hindrance, radical attack at the relatively strong π-bond of isonitriles is assisted by chame- leonic supramolecular interactions of the radical center with both the isonitrile π*-system and carbon’s lone pair. These interactions are yet another manifestation of supramolecular control of radical chemistry [3]. This work was supported by National Science Foundation, CHE-1800329 References [1] Nenajdenko, V. (Ed.) Isocyanide Chemistry; Wiley-VCH Verlag & Co. KGaA: Weinheim, Germany, 2012. [2] Vatsadze, S.; Loginova, Y.; Gomes, G.; Alabugin, I. Chem. Eur. J., 2017, 23(14), 3225. [3] Gomes, G.; Loginova, Y.; Vatsadze, S.; Alabugin, I. JACS, 2018, 140(43), 14272.