1217435-93-2

Upstream product

• 622-76-4 1-phenyl-1-butyne 
• 73183-34-3 bis(pinacol)diborane 
• 25015-63-8 4,4,5,5-tetramethyl-[1,3,2]-dioxaboralane 
• 32644-22-7 1-methyl-3-phenylallene 

Relevant academic research and scientific papers

Bis(imidazoline-2-thione)-copper(i) catalyzed regioselective boron addition to internal alkynes

New catalytic systems based on a bis(1,3-disubstituted imidazoline 2-thione)-copper complex have been developed for the highly regioselective boration of internal alkynes.

Linear Cu(I) chalcogenones: Synthesis and application in borylation of unsymmetrical alkynes

The syntheses and structures of copper(i) chalcogenone complexes are described. The homoleptic mononuclear copper(i) complexes [(IPrE)2Cu]ClO4, IPrE, 1,3-bis(2,6-diisopropylphenyl)imidazoline-2-thione (1) and 1,3-bis(2,6-diisopropylphenyl)imidazoline-2-selone (2); [(IMesE)2Cu]ClO4, IMesE, 1,3-bis(2,4,6-trimethylphenyl)imidazole-2-thione (3) and 1,3-bis(2,4,6-trimethylphenyl)imidazole-2-selone (4); [(IPrE)2Cu]BF4, E = S (5); E = Se (6) and [(IMesE)2Cu]BF4, E = S (7); E = Se (8) are formed from the reduction of copper(ii) to copper(i) with the corresponding imidazoline-2-chalcogenones. X-ray structure analyses of seven compounds (1-3 and 5-8) show that the copper(i) ion is in a perfect linear coordination, while 4 is in quasi-linear geometry. Molecules 2, 4, 6 and 8 are the first structurally characterized homoleptic copper(i) selone complexes. The optical and thermal properties of imidazoline-2-chalcogenones and their copper(i) derivatives are investigated. These complexes are able to act as catalysts in regioselective borylation 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.

Ligand-controlled cobalt-catalyzed regiodivergent hydroboration of aryl,alkyl-disubstituted internal allenes

We report a stereoselective regiodivergent hydroboration of aryl,alkyl-disubstituted internal allenes with pinacolborane (HBpin) in the presence of cobalt catalysts generated from bench-stable Co(acac)2 and bisphosphine ligands. An interesting correlation between the regioselectivity of this hydroboration and the bite angles of bisphosphine ligands was identified. When hydroboration was conducted with cobalt catalysts containing bisphosphines with medium bite angles (e.g. 98° for dppb and 96° for dppf), HBpin was selectively added to the alkyl-substituted double bond. However, HBpin was selectively added to the aryl-substituted double bond when the reactions were conducted with cobalt catalysts containing bisphosphines with large bite angles (e.g. 111° for xantphos and 114° for Nixantphos). A range of internal allenes underwent these Co-catalyzed hydroboration reactions in a regiodivergent manner to yield the corresponding (Z)-alkenylboronates in high isolated yields and with high regioselectivity. These reactions show good functional group compatibility and can be readily scaled up to gram scales without using a dry box. In addition, the comparison of regioselectivity between the Co-catalyzed hydrosilylation and hydroboration reactions of the same allene substrate suggests that this Co-catalyzed regiodivergent hydroboration of allenes proceeds through a Co-Bpin intermediate. Deuterium-labeling experiments suggest that the Co-Bpin intermediates react with allenes to form allylcobalt species which then react with HBpin to release (Z)-alkenylboronate products.

Cyclodextrin Cavity-Induced Mechanistic Switch in Copper-Catalyzed Hydroboration

N-heterocyclic carbene-capped cyclodextrin (ICyD) ligands, α-ICyD and β-ICyD derived from α- and β-cyclodextrin, respectively give opposite regioselectivities in a copper-catalyzed hydroboration. The site-selectivity results from two different mechanisms: the conventional parallel one and a new orthogonal mechanism. The shape of the cavity was shown not only to induce a regioselectivity switch but also a mechanistic switch. The scope of interest of the encapsulation of a reactive center is therefore broadened by this study.

Iron-Catalyzed Hydroboration: Unlocking Reactivity through Ligand Modulation

Iron-catalyzed hydroboration (HB) of alkenes and alkynes is reported. A simple change in ligand structure leads to an extensive change in catalyst activity. Reactions proceed efficiently over a wide range of challenging substrates including activated, unactivated and sterically encumbered motifs. Conditions are mild and do not require the use of reducing agents or other additives. Large excesses of borating reagent are not required, allowing control of chemo- and regioselectivity in the presence of multiple double bonds. Mechanistic insight reveals that the reaction is likely to proceed via a highly reactive iron hydride intermediate.

Ligand-free hydroboration of alkynes catalyzed by heterogeneous copper powder with high efficiency

Regioselective hydroboration of terminal and internal alkynes is realized by using 10 mol% copper powder (0.3-1 μm) at room temperature. 24 alkynes were efficiently converted into vinylboronates in up to 96% yield without addition of any ligand or additiv

Highly regio- and stereoselective synthesis of alkenylboronic esters by copper-catalyzed boron additions to disubstituted alkynes

The copper-catalyzed addition of bis(pinacolato)diboron to internal alkynes in the presence of methanol generates alkenylboron compounds with high levels of regio- and stereoselectivities. The catalytic efficiency is increased by using monodentate phosphine ligands, especially P(p-tolyl)3 and a range of internal alkynes was borylated in good yields. The Royal Society of Chemistry.