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。
Stereodivergent Access to Trisubstituted Alkenylboronate Esters through Alkene Isomerization
作者:Lucas Segura、Itai Massad、Masamichi Ogasawara、Ilan Marek
DOI:10.1021/acs.orglett.1c03513
日期:2021.12.3
We report an efficient method for the preparation of synthetically valuable trisubstituted alkenylboronate esters through alkene isomerization of their readily available 1,1-disubstituted regioisomeric counterparts. Either stereoisomer of the target alkenylboronate motif can be obtained at will from the same starting material by employing different isomerization catalysts.
cycloalkanes have been reported. Zard reported an example of a two-step procedure involving xanthate transfer radicaladdition to a vinyl MIDA boronate, followed by an intramolecular homolyticaromaticsubstitution reaction on a thiophene.21 Norton and coll. reported an interesting cobaloxime catalyzed radical cycloisomerization process leading to borylated 5-membered rings (Scheme 1, B). Lin et al. reported
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
作者:Kong, Ziyin、Park, Jimin、Fei, Muchun、Warfield, Josephine、Wang, Dunwei、Morken, James P.
DOI:10.1055/s-0043-1774906
日期:——
A practical method is introduced for the catalytic conversion of terminal alkynes into α-substituted vinyl boronic esters. The process employs catalytic amounts of nanoparticle-supported gold catalysts and catalytic amounts of copper to effect the overall transformation.