74213-47-1Relevant academic research and scientific papers
Stable, Yet Highly Reactive Nonclassical Iron(II) Polyhydride Pincer Complexes: Z-Selective Dimerization and Hydroboration of Terminal Alkynes
Gorgas, Nikolaus,Alves, Luis G.,St?ger, Berthold,Martins, Ana M.,Veiros, Luis F.,Kirchner, Karl
, p. 8130 - 8133 (2017)
The synthesis, characterization, and catalytic activity of nonclassical iron(II) polyhydride complexes containing tridentate PNP pincer-type ligands is described. These compounds of the general formula [Fe(PNP)(H)2(η2-H2)]
Zwitterion-Initiated Hydroboration of Alkynes and Styrene
Bismuto, Alessandro,Cowley, Michael J.,Thomas, Stephen P.
supporting information, p. 2382 - 2385 (2021/01/18)
The hydroboration of alkynes and styrene with HBpin has been developed using tris(pentaflurophenyl)borane (B(C6F5)3) as the initiator of catalysis. The hydroboration is proposed to be initiated by Lewis acid activation of the alkyne by (B(C6F5)3) to form a highly reactive zwitterionic species which subsequently react with HBpin to give the alkenyl boronic ester. This zwitterion has also showed potential to be a competent catalyst for the hydroboration of styrene. The zwitterionic intermediate is analogous to that proposed in the Piers borane-catalysed hydroboration and 1,1-carboboration of alkynes with B(C6F5)3. (Figure presented.).
Z-Selective Alkyne Functionalization Catalyzed by a trans-Dihydride N-Heterocyclic Carbene (NHC) Iron Complex
De Ruiter, Graham,Fridman, Natalia,Garhwal, Subhash
supporting information, p. 13817 - 13821 (2020/10/09)
The Z-selective functionalization of terminal alkynes is a useful transformation in organic chemistry and mainly catalyzed by noble metals. Here, we present the Z-selective hydroboration of terminal alkynes catalyzed by a stable trans-dihydride iron compl
Pd-catalyzed hydroborylation of alkynes: A ligand controlled regioselectivity switch for the synthesis of α- Or β-vinylboronates
Ojha, Devi Prasan,Prabhu, Kandikere Ramaiah
supporting information, p. 432 - 435 (2016/02/18)
A ligand controlled selective hydroborylation of alkynes to α- or β-vinylboronates has been developed using a Pd catalyst. The high α-selectivity displayed by this reaction can be switched to furnish β-vinylboronates by altering the ligand from a trialkylphosphine to N-heterocyclic carbene. A variety of terminal alkynes are shown to furnish the corresponding α- or β-vinylboronates in good to excellent selectivity and yield. The mechanistic studies suggest that the solvent is the proton source and bromobenzene functions as an important additive in driving this reaction forward.
Linear Cu(I) chalcogenones: Synthesis and application in borylation of unsymmetrical alkynes
Srinivas, Katam,Naga Babu, Chatla,Prabusankar, Ganesan
, p. 15636 - 15644 (2015/09/07)
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.
Rhodium-catalyzed dehydrogenative borylation of aliphatic terminal alkenes with pinacolborane
Morimoto, Masao,Miura, Tomoya,Murakami, Masahiro
supporting information, p. 12659 - 12663 (2015/10/28)
Aliphatic terminal alkenes react with pinacolborane at ambient temperature to afford dehydrogenative borylation compounds as the major product when iPr-Foxap is used as the ligand with cationic rhodium(I) in the presence of norbornene, which acts as the s
Cobalt Catalyzed Z -Selective Hydroboration of Terminal Alkynes and Elucidation of the Origin of Selectivity
Obligacion, Jennifer V.,Neely, Jamie M.,Yazdani, Aliza N.,Pappas, Iraklis,Chirik, Paul J.
supporting information, p. 5855 - 5858 (2015/05/27)
A bis(imino)pyridine cobalt-catalyzed hydroboration of terminal alkynes with HBPin (Pin = pinacolate) with high yield and (Z)-selectivity for synthetically valuable vinylboronate esters is described. Deuterium labeling studies, stoichiometric experiments, and isolation of catalytically relevant intermediates support a mechanism involving selective insertion of an alkynylboronate ester into a Co-H bond, a pathway distinct from known precious metal catalysts where metal vinylidene intermediates have been proposed to account for the observed (Z) selectivity. The identity of the imine substituents dictates the relative rates of activation of the cobalt precatalyst with HBPin or the terminal alkyne and, as a consequence, is responsible for the stereochemical outcome of the catalytic reaction.
Regulation of Iron-Catalyzed Olefin Hydroboration by Ligand Modifications at a Remote Site
Tseng, Kuei-Nin T.,Kampf, Jeff W.,Szymczak, Nathaniel K.
, p. 411 - 415 (2015/04/27)
An amide-derived N,N,N-Fe(II) complex catalyzes the hydroboration of alkenes at room temperature. Alkylation of a remote site on the ligand backbone was used as a late-stage modification to provide a more electrophilic complex as determined by electrochemical studies. The alkylated variant, compared to the parent complex, catalyzes olefin hydroboration with an increased reaction rate and exhibits distinct regioselectivity for internal alkene hydroboration. (Figure Presented).
PSiP-pincer type palladium-catalyzed dehydrogenative borylation of alkenes and 1,3-Dienes
Kirai, Naohiro,Iguchi, Shoichiro,Ito, Tatsuyoshi,Takaya, Jun,Iwasawa, Nobuharu
, p. 784 - 799 (2013/08/23)
Dehydrogenative borylation of alkenes and 1,3-dienes was realized by carrying out the reaction in the presence of bis(pinacolato)diboron (B2pin2) and a catalytic amount of PSiP-pincer palladium complex. This protocol has the following notable features. 1)
Catalytic non-conventional trans-hydroboration: A theoretical and experimental perspective
Cid, Jessica,Carbo, Jorge J.,Fernandez, Elena
supporting information; experimental part, p. 1512 - 1521 (2012/03/27)
We have studied the nonconventional trans-hydroboration reaction of alkynes both experimentally and theoretically. A catalytic system based on the in situ mixture of [{Rh- (cod)Cl}2]/PCy3 (cod=1,5-cyclooctadiene, Cy=cyclohexyl) has been able to activate pinacolborane and catecholborane and transfer boryl and hydride groups onto the same unhindered carbon atom of the terminal alkynes. The presence of a base (Et3N) favored the non-conventional trans-hydroboration over the traditional cis-hydroboration. Varying the substrate had a significant influence on the reaction, with up to 99% conversion and 94% regioselectivity observed for para-methyl- phenylacetylene. Both DFT and quantum mechanical/molecular mechanical ONIOM calculations were carried out on the [RhCl(PR3)2] system. To explain the selectivity towards the (Z)-alkenylboronate we explored several alternative mechanisms to the traditional cishydroboration, using propyne as a model alkyne. The proposed mechanism can be divided into four stages: 1) isomerization of the alkyne into the vinylidene, 2) oxidative addition of the borane reagent, 3) vinylidene insertion into the Rh-H bond, and finally 4) reductive elimination of the C-B bond to yield the 1-alkenylboronate. Calculations indicated that the vinylidene insertion is the selectivity- determining step. This result was consistent with the observed Z selectivity when the sterically demanding phosphine groups, such as PCy3 and PiPr3, were introduced. Finally, we theoretically analyzed the effect of the substrate on the selectivity; we identified several factors that contribute to the preference for aryl alkynes over aliphatic alkynes for the Z isomer. The intrinsic electronic properties of aryl substituents favored the Z-pathway over the E-pathway, and the aryl groups containing electron donating substituents favored the occurrence of the vinylidene reaction channel.
