562098-10-6Relevant articles and documents
Hydroboration of Terminal Alkenes and trans-1,2-Diboration of Terminal Alkynes Catalyzed by a Manganese(I) Alkyl Complex
Kirchner, Karl,St?ger, Berthold,Veiros, Luis F.,Weber, Stefan,Zobernig, Daniel
supporting information, p. 24488 - 24492 (2021/10/19)
A MnI-catalyzed hydroboration of terminal alkenes and a 1,2-diboration of terminal alkynes with pinacolborane (HBPin) is described. For alkenes, anti-Markovnikov hydroboration takes place; for alkynes the reaction proceeds with excellent trans-1,2-selectivity. The most active pre-catalyst is bench-stable alkyl bisphosphine MnI complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn–alkyl bond to yield an acyl intermediate, which undergoes B?H bond cleavage of HBPin (for alkenes) and rapid C?H bond cleavage (for alkynes), forming the active MnI boryl and acetylide catalysts [Mn(dippe)(CO)2(BPin)] and [Mn(dippe)(CO)2(C≡CR)], respectively. A broad variety of aromatic and aliphatic alkenes and alkynes was efficiently and selectively borylated. Mechanistic insights are provided based on experimental data and DFT calculations revealing that an acceptorless reaction is operating involving dihydrogen release.
Regio- and stereocontrolled access to ?-boronated unsaturated amino esters and derivatives from (z)-alkenyl 1,2-bis(boronates)
Sridhar, Tailor,Berree, Fabienne,Sharma, Gangavaram V. M.,Carboni, Bertrand
, p. 783 - 789 (2014/04/03)
The Borono-Mannich reaction of (Z)-1-alkene-1,2-diboronic esters proceeded regioselectively at the terminal C-B bond to afford (E)-?-boronated unsaturated amino esters in good yields. These compounds were then subjected to Suzuki couplings for the creatio
Synthesis and characterization of platinum(II)-Bis(boryl) catalyst precursors for diboration of alkynes and diynes: Molecular structures of cis-[(PPh3)2Pt(B-4-Butcat)2], cis-[(PPh3)2Pt(Bcat)2], cis-[(dppe)Pt(Bcat)2], cis-[(dppb)Pt(Bcat)2]
Lesley, Gerry,Nguyen, Paul,Taylor, Nicholas J.,Marder, Todd B.,Scott, Andrew J.,Clegg, William,Norman, Nicholas C.
, p. 5137 - 5154 (2008/10/08)
The reactions of the B-B-bonded compounds B2(cat)2 (cat = 1,2-O2C6H4) (1a), B2(4-But-cat)2 (1b), and B2(OCMe2CMe2O)2 (1c) with the Pt(0)-bis(phosphine) complex [(PPh3)2Pt(η-C2H4)] (4) via oxidative addition of the B-B bond yield cis-bis(boryl) Pt(II) complexes. The molecular structures of cis-[(PPh3)2Pt(Bcat)2]·C 6D6 (3a) and cis-[(PPh3)2Pt(B-4-Butcat)2] (3b) were determined by single-crystal X-ray diffraction. Reaction of 3a with 1 equiv of the bidentate phosphine dppe (Ph2PCH2CH2PPh2) or dppb (Ph2P(CH2)4PPh2) proceeds smoothly in toluene to give cis-[(dppe)Pt(Bcat)2] (5a) and cis-[(dppb)Pt(Bcat)2] (5b), respectively, which have also been characterized by X-ray diffraction. Compounds 3a,b and 4 are highly active catalyst precursors for the diboration of alkynes and 1,3-diynes. X-ray crystal structures of (E)-(4-MeOC6H4)C(Bcat)=CH(Bcat) (10c), (Z)-(C6H5)C(Bcat)=C(C6H5)(Bcat) (10e), and (Z,Z)-(4-MeOC6H4)C(Bcat)=C(Bcat)C(Bcat)=C(4-MeOC 6H4)(Bcat) (14a) confirm the cis stereochemistry of the boron substituents in three representative cases, namely, products of the catalyzed diboration of the terminal alkyne 4-MeOC6H4C=CH, the internal alkyne PhC=CPh, and the tetraboration of the diyne 4,4′-MeOC6H4C=CC=CC6H4OMe. The presence of the C=CSiMe3 moiety in catalytic reactions gives rise to additional products other than those derived from the diboration of the alkyne group. Metathetical reactions involving the diboron reagent and products derived from C-Si bond cleavage give rise to novel tris(boronate esters) as a result of the subsequent diboration of the C=CB(OR2) moieties formed by this competing process. The absence of catalytic activity using compound 5a, the extremely low activity of 5b, and the strong decrease in activity of 3b in the presence of added PPh3 suggests that phosphine dissociation is a critical step in the catalytic pathway.