791845-45-9Relevant academic research and scientific papers
Copper(ii)-catalyzed protoboration of allenes in aqueous media and open air
Nekvinda, Jan,Santos, Webster L.,Snead, Russell F.
, p. 14925 - 14931 (2021/09/04)
A method has been developed for the facile Cu(ii)-catalyzed protoboration of monosubstituted allenes in aqueous media under atmospheric conditions. The reaction occurs site selectively, favoring internal alkene protoboration to afford 1,1-disubstituted vinylboronic acid derivatives (up to 93?:?7) with modest to good yields. The method has been applied to a variety of phenylallene derivatives as well as alkyl-substituted allenes. This journal is
Stereoselective formation of trisubstituted vinyl boronate esters by the acid-mediated elimination of α-hydroxyboronate esters
Guan, Weiye,Michael, Alicia K.,McIntosh, Melissa L.,Koren-Selfridge, Liza,Scott, John P.,Clark, Timothy B.
, p. 7199 - 7204 (2014/08/18)
The copper-catalyzed diboration of ketones followed by an acid-catalyzed elimination leads to the formation of 1,1-disubstituted and 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.
Copper-catalyzed highly regio- and stereoselective directed hydroboration of unsymmetrical internal alkynes: Controlling regioselectivity by choice of catalytic species
Semba, Kazuhiko,Fujihara, Tetsuaki,Terao, Jun,Tsuji, Yasushi
, p. 4179 - 4184 (2012/05/31)
A highly selective synthesis of the αand β products by copper-catalyzed hydroboration utilizing two different catalytic copper species generated from pinacolborane (HBpin) and B2pin2 is reported. Regioselectivity in the crude reaction mixtures is found to be high, and the corresponding a products were isolated in good yields. In the case of an alkyne containing an alkenyl moiety, the regioselectivity decreased to 72:28. In hydroboration reactions catalyzed by other transition metals, selecting between hydrometalation and boryl metalation is difficult because the oxidative addition of HB to a metal center provides an H-M-B species, containing both H-M and B-M bonds. The α and β products are valuable intermediates used in the Suzuki-Miyaura cross-coupling reaction to regioselectively prepare various trisubstituted alkenes of types 5α and 5β.
Regiocontrolled CuI-catalyzed borylation of propargylic- functionalized internal alkynes
Moure, Abraham L.,Gomez Arrayas, Ramon,Cardenas, Diego J.,Alonso, Ines,Carretero, Juan C.
, p. 7219 - 7222 (2012/06/16)
Good to excellent reactivity and regiocontrol have been achieved in the CuI-catalyzed borylation of dialkyl internal alkynes with bis(pinacolato)diboron. The presence of a propargylic polar group (OH, OR, SAr, SO2Ar, or NHTs), in combination with PCy3 as ligand, allowed maximizing the reactivity and site-selectivity (β to the propargylic function). DFT calculations suggest a subtle orbitalic influence from the propargylic group, matched with ligand and substrate size effects, as key factors involved in the high β-selectivity. The vinylboronates allowed the stereoselective synthesis of trisubstituted olefins, while allylic substitution of the SO2Py group without affecting the boronate group provided access to formal hydroboration products of unbiased dialkylalkynes.
CuCl-K2CO3-catalyzed highly selective borylcupration of internal alkynes - Ligand effect
Yuan, Weiming,Ma, Shengming
supporting information; experimental part, p. 7266 - 7268 (2012/10/07)
An efficient and practical copper-catalyzed highly regio- and stereoselective borylcupration of internal alkynes with bis(pinacolato)diboron using a catalytic amount of K2CO3 as base producing Z-alkenylboron compounds has been demonstrated by applying the ligand effect: commercially available electron-rich tris(p-methoxyphenyl) phosphine ensures a smooth and efficient reaction. Functionalized alkynes, such as propargylic alcohols and derivatives as well as N-propargyl tosylamide, may also be used with excellent selectivity.
