Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
Chemistry. 2013 Mar 4;19(10):3504-11. doi: 10.1002/chem.201203646. Epub 2013 Jan 23.
In intermolecular Heck reactions of styrene and vinylarenes, the aryl and vinyl groups routinely insert at the β position. However, selective insertion at the α position has been very rare. Herein, we provide a missing piece in the palette of Heck reaction, which gave >20:1 α selectivity. The key to our success is a new ferrocene 1,1'-bisphosphane (dnpf) that carries 1-naphthyl groups. Our mechanistic studies revealed that the high α selectivity is partly attributable to the steric effect of dnpf. The rigid and bulky 1-naphthyl groups of dnpf sterically disfavor β insertion.
在苯乙烯和乙烯基芳烃的分子间 Heck 反应中，芳基和乙烯基基团通常在β位插入。然而，选择性地在α位插入的情况非常罕见。在此，我们提供了 Heck 反应调色板中缺失的一环，该反应获得了 >20:1 的α选择性。我们成功的关键是一种新型二茂铁 1,1'-双膦（dnpf），它带有 1-萘基。我们的机理研究表明，高的α选择性部分归因于 dnpf 的空间位阻效应。dnpf 的刚性和庞大的 1-萘基基团在空间上不利于β插入。
