1003865-86-8Relevant articles and documents
3-(Dimethylboryl)pyridine: Synthesis, structure, and remarkable steric effects in scrambling reactions
Wakabayashi, Shigeharu,Imamura, Saori,Sugihara, Yoshikazu,Shimizu, Makoto,Kitagawa, Toshikazu,Ohki, Yasuhiro,Tatsumi, Kazuyuki
, p. 81 - 87 (2008)
(Chemical Equation Presented) A facile method for the synthesis of 3-(dimethylboryl)pyridine (1a) is described. Compound 1a assembles into a rigid cyclic tetramer stabilized via intermolecular boron-nitrogen coordination bonds both in the crystalline state and in solution. The outstanding structural feature of 1a, as compared with previously reported 3-(diethylboryl)pyridine (2a) (which adopts a cone conformation), is that the tetramer of la adopts a 1,2-alternate conformation. To investigate the effect of substituents at the boron atom on the stabilities of the oligomers, scrambling experiments of the component molecules using 1, 2, and 3-(di-n-butylboryl)pyridines 3 were carried out. Although heating at 80-90°C for 20 h was required to attain the equilibrium of the scrambling reactions when the component molecules of the tetramers were 2 or 3, the scrambling in 1 proceeded under relatively mild conditions (60°C, 3 h). This difference in reaction conditions required for 1, as compared to conditions required for 2 or 3, could not be explained solely by the stabilities based on bond lengths or THC.1g It appears that whereas only an SN1-type pathway may be involved in the scrambling of 2 or 3, both SN1- and SN2-type mechanisms operate simultaneously during scrambling reactions of 1 or an intermediate mechanism between SN1 and SN2 operates, which was supported by kinetic studies and calculations using model compounds.
