Gómez-Suárez Adrián, Oonishi Yoshihiro, Martin Anthony R, Nolan Steven P
EaStCHEM School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, Fife, KY16 9ST, U.K.
EaStCHEM School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, Fife, KY16 9ST, U.K; Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
Beilstein J Org Chem. 2016 Feb 1;12:172-8. doi: 10.3762/bjoc.12.19. eCollection 2016.
Due to the synthetic advantages presented by the dual-gold-catalysed hydrophenoxylation of alkynes, a thorough study of this reaction was carried out in order to fully define the scope and limitations of the methodology. The protocol tolerates a wide range of functional groups, such as nitriles, ketones, esters, aldehydes, ketals, naphthyls, allyls or polyphenols, in a milder and more efficient manner than the previously reported methodologies. We have also identified that while we are able to use highly steric hindered phenols, small changes on the steric bulk of the alkynes have a dramatic effect on the reactivity. More importantly, we have observed that the use of substrates that facilitate the formation of diaurated species such as gem-diaurated or σ,π-digold-acetylide species, hinder the catalytic activity. Moreover, we have identified that the use of directing groups in unsymmetrical alkynes can help to achieve high regioselectivity in the hydrophenoxylation.
由于炔烃的双金催化氢酚氧基化反应所呈现出的合成优势，我们对该反应进行了深入研究，以全面确定该方法的适用范围和局限性。与先前报道的方法相比，该方案能够以更温和、更高效的方式兼容多种官能团，如腈基、酮基、酯基、醛基、缩酮、萘基、烯丙基或多酚。我们还发现，虽然我们能够使用空间位阻较大的酚类，但炔烃空间位阻的微小变化对反应活性有显著影响。更重要的是，我们观察到，使用有助于形成双金物种（如偕双金物种或σ,π-二金乙炔物种）的底物会阻碍催化活性。此外，我们还发现，在不对称炔烃中使用导向基团有助于在氢酚氧基化反应中实现高区域选择性。
