title: Undeniable Confirmation of the syn-Addition Mechanism for Metal-Free Diboration by Using the Crystalline Sponge Method.
abstract: The stereochemical outcome of the recently developed metal-free 1,2-diboration of aliphatic alkenes has, until now, only been elucidated by indirect means (e.g. derivatization). This is because classical conformational analysis of the resulting 1,2-diboranes is not viable; in the (1)H NMR spectrum the relevant (1)H resonances are broadened by (11)B, and the occurrence of the products as oily compounds precludes X-ray crystallographic analysis. Herein, the crystalline sponge method is used to display the crystal structures of the diboronic esters formed from internal E and Z olefins, evidencing the stereospecific syn addition mechanism of the reaction, which is fully consistent with the prediction from DFT calculations.
authors: Department Quimica Física i Inorgànica, University Rovira i Virgili, C/Marcel⋅lí Domingo s/n, 43007, Tarragona, Spain.
authors: Ana B
authors: AB
authors: Cuenca
authors: Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors: Nicolas
authors: N
authors: Zigon
authors: Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors: Vincent
authors: V
authors: Duplan
authors: Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors: Manabu
authors: M
authors: Hoshino
authors: Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan. mfujita@appchem.t.u-tokyo.ac.jp.
authors: Makoto
authors: M
authors: Fujita
authors: Department Quimica Física i Inorgànica, University Rovira i Virgili, C/Marcel⋅lí Domingo s/n, 43007, Tarragona, Spain. mariaelena.fernandez@urv.cat.
authors: Elena
authors: http://orcid.org/0000-0001-9025-1791
authors: E
authors: Fernández
keywords: 1,2-diboron; configuration; crystalline sponge method; diboron inclusion; organocatalysis