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Undeniable Confirmation of the syn ‐Addition Mechanism for Metal‐Free Diboration by Using the Crystalline Sponge Method
Author(s) -
Cuenca Ana B.,
Zigon Nicolas,
Duplan Vincent,
Hoshino Manabu,
Fujita Makoto,
Fernández Elena
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201600392
Subject(s) - stereospecificity , sponge , derivatization , chemistry , metal , crystal structure , stereochemistry , reaction mechanism , mechanism (biology) , crystallography , organic chemistry , catalysis , physics , botany , high performance liquid chromatography , biology , quantum mechanics
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.