Fasano Valerio, Cid Jessica, Procter Richard J, Ross Emily, Ingleson Michael J
School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Angew Chem Int Ed Engl. 2018 Oct 1;57(40):13293-13297. doi: 10.1002/anie.201808216. Epub 2018 Sep 10.
An intramolecular 1,2-boryl-anion migration from boron to carbon has been achieved by selective activation of the π system in [(vinyl)B Pin )] using "soft" BR electrophiles (BR =BPh or 9-aryl-BBN). The soft character is key to ensure 1,2-migration proceeds instead of oxygen coordination/B-O activation. The BR -induced 1,2-boryl-anion migration represents a triple borylation of a vinyl Grignard reagent using only B Pin and BR and forms differentially protected 1,1,2-triborylated alkanes. Notably, by increasing the steric bulk at the β position of the vinyl Grignard reagent used to activate B Pin , 1,2-boryl-anion migration can be suppressed in favor of intermolecular {BPin} transfer to BPh , thus enabling simple access to unsymmetrical sp -sp diboranes.
通过使用“软”BR亲电试剂（BR = BPh或9-芳基-BBN）选择性活化[(乙烯基)B Pin)]中的π体系，实现了分子内1,2-硼阴离子从硼到碳的迁移。软特性是确保发生1,2-迁移而不是氧配位/B-O活化的关键。BR诱导的1,2-硼阴离子迁移代表仅使用B Pin和BR对乙烯基格氏试剂进行的三次硼化反应，并形成差异保护的1,1,2-三硼化烷烃。值得注意的是，通过增加用于活化B Pin的乙烯基格氏试剂β位的空间位阻，可以抑制1,2-硼阴离子迁移，有利于分子间{BPin}转移到BPh，从而能够简便地获得不对称sp -sp二硼烷。
