The hydroboration of terminal allenes with pinacolborane was carried out at 50 °C in the presence of a Pt(dba)2/2PR3 catalyst. The formation of one of three possible monohydroboration products was regioselectively synthesized by choosing an appropriate phosphine ligand.
thermal properties of imidazoline-2-chalcogenones and their copper(I) derivatives are investigated. These complexes are able to act as catalysts in regioselectiveborylation of numerous unsymmetrical alkynes, yielding synthetically useful vinylboronates. Among catalysts 1–8, catalyst 4 is highly selective towards the regioselective boron addition of 1-phenyl-1-propyne.
Stereoselective Formation of Trisubstituted Vinyl Boronate Esters by the Acid-Mediated Elimination of α-Hydroxyboronate Esters
作者:Weiye Guan、Alicia K. Michael、Melissa L. McIntosh、Liza Koren-Selfridge、John P. Scott、Timothy B. Clark
DOI:10.1021/jo500773t
日期:2014.8.1
trisubstituted vinyl boronate esters with moderate to good yields and selectivity. Addition of tosic acid to the crude diboration products provides the corresponding vinyl boronate esters upon elimination. The trisubstituted vinyl boronate esters are formed as the (Z)-olefin isomer, which was established by subjecting the products to a Suzuki–Miyaura coupling reaction to obtain alkenes of known geometry
铜催化酮的二硼化,然后是酸催化的消除,导致形成 1,1-二取代和三取代乙烯基硼酸酯,具有中等至良好的产率和选择性。将甲苯磺酸加入粗二硼化产物中,消除后得到相应的硼酸乙烯酯。三取代的乙烯基硼酸酯形成为 ( Z )-烯烃异构体,这是通过将产物进行 Suzuki-Miyaura 偶联反应以获得已知几何形状的烯烃来建立的。
Pincer Iron Hydride Complexes for Alkene Isomerization: Catalytic Approach to Trisubstituted (<i>Z</i>)-Alkenyl Boronates
phosphine–pyridine–imidazoline (PNNimid) ligand [Fe]Cl2 = (PNNimid)FeCl2}, upon activation with NaHBEt3, catalyzes the isomerization of 1,1-disubstituted alkenyl boronates to synthetically valuable but previously difficult-to-access trisubstituted (Z)-alkenyl boronates with excellent regio- and stereoselectivity. The loading of the catalyst activator relative to iron was found to affect the selectivity and