Regio‐ and Stereoselective Homologation of 1,2‐Bis(Boronic Esters): Stereocontrolled Synthesis of 1,3‐Diols and Sch 725674
作者:Alexander Fawcett、Dominik Nitsch、Muhammad Ali、Joseph M. Bateman、Eddie L. Myers、Varinder K. Aggarwal
DOI:10.1002/anie.201608406
日期:2016.11.14
1,2-Bis(boronic esters), derived from the enantioselective diboration of terminal alkenes, can be selectively homologated at the primary boronic ester by using enantioenriched primary/secondary lithiated carbamates or benzoates to give 1,3-bis(boronic esters), which can be subsequently oxidized to the corresponding secondary-secondary and secondary-tertiary 1,3-diols with full stereocontrol. The transformation
Bis(pinacolato)diboron selectively adds to terminal alkenes and cyclic
alkenes having internal strain to provide bis(boryl)alkanes in
76–86% yields in the presence of a catalytic amount of
Pt(dba)
2
at 50 °C.
New expanded-ring NHC platinum(0) complexes: Synthesis, structure and highly efficient diboration of terminal alkenes
作者:Sergey A. Rzhevskiy、Maxim A. Topchiy、Konstantin A. Lyssenko、Anna N. Philippova、Maria A. Belaya、Alexandra A. Ageshina、Maxim V. Bermeshev、Mikhail S. Nechaev、Andrey F. Asachenko
DOI:10.1016/j.jorganchem.2020.121140
日期:2020.4
The synthesis and structural characterization of a series of novel platinum(0) complexes were reported. A number of (NHC)Pt(dvtms) (dvtms = 1,3-divinyl-1,1,3,3-tetramethyldisiloxane) complexes were investigated in catalytic addition of B2Pin2 to terminal alkenes. The novel expanded ring N-heterocyclic carbene complex (7-Dipp)Pt(dvtms) showed highest performance, turnover numbers up to 3800 were achieved
Although transition-metal-catalysed hydroboration reactions of alkenes have been extensively studied, only three examples using Ni complexes have been reported so far. In this study, we have examined hydroboration reactions of alkenes using Ni/phosphine complexes. The commercially available and bottleable complex NiCl2(dppe) (dppe = 1,2-bis(diphenylphosphino)ethane) serves as a catalyst for the highly
Highly efficient monophosphine platinum catalysts for alkyne diboration
作者:Rhodri Ll. Thomas、Fabio E. S. Souza、Todd B. Marder
DOI:10.1039/b010225n
日期:——
Automated parallel screening using a series of in situ generated platinum(0) phosphine complexes has allowed the identification of improved catalysts for the diboration of alkynes using bis(pinacolato)diboron (B2(pin)2, pin = OCMe2CMe2O). A selection of phosphines were added to [Pt(NBE)3] (NBE = norbornene), which contains only labile mono-olefin ligands, and the activity of the resulting solutions as catalysts for the diboration of 4-CF3C6H4CCC6H4CF3-4′
1 by B2(pin)2 was investigated by in situ GC-MS and/or NMR spectroscopy. This allowed the optimum phosphine ∶ platinum stoichiometry to be identified as 1 ∶ 1, and the large differences in catalyst activity depending on the nature of the phosphine to be quantified. The best phosphines employed in the study, PCy3 and PPh2(o-Tol) (o-Tol = C6H4Me-o), give activities orders of magnitude greater than the worst, such as P(C6F5)3 and PBut3. The monophosphine catalysts function much more efficiently than previous catalysts for a range of alkynes allowing diborations to be performed at ambient temperatures. The diboration of strained cyclic alkenes and some vinyl- and allyl-arenes proceeded well, although the catalysts were inactive for other olefinic systems examined. As a result of these studies, the isolable and stable compound [Pt(PCy3)(η2-C2H4)2] was identified as an excellent catalyst for alkyne diboration even at room temperature.
p