581802-24-6Relevant articles and documents
Direct Synthesis of Alkenylboronates from Alkenes and Pinacol Diboron via Copper Catalysis
Lu, Wenkui,Shen, Zengming
supporting information, p. 142 - 146 (2019/01/11)
We report an efficient approach for the direct synthesis of alkenylboronates using copper catalysis. The Cu/TEMPO catalyst system (where TEMPO = (2,2,6,6-tetramethylpiperidin-1-yl)oxyl) exhibits both excellent reactivity and selectivity for the synthesis of alkenylboronates, starting from inexpensive and abundant alkenes and pinacol diboron. This approach allows for the direct functionalization of both aromatic and aliphatic terminal alkenes. Mechanistic experiments suggest that the alkenylboronates arise from oxyboration intermediates.
Highly selective methods for synthesis of internal (α-) vinylboronates through efficient NHC-Cu-catalyzed hydroboration of terminal alkynes. Utility in chemical synthesis and mechanistic basis for selectivity
Jang, Hwanjong,Zhugralin, Adil R.,Lee, Yunmi,Hoveyda, Amir H.
, p. 7859 - 7871 (2011/06/27)
Cu-catalyzed methods for site-selective hydroboration of terminal alkynes, where the internal or α-vinylboronate is generated predominantly (up to >98%) are presented. Reactions are catalyzed by 1-5 mol % of N-heterocyclic carbene (NHC) complexes of copper, easily prepared from N-aryl-substituted commercially available imidazolinium salts, and proceed in the presence of commercially available bis(pinacolato)diboron [B2(pin)2] and 1.1 equiv of MeOH at -50 to -15 °C in 3-24 h. Propargyl alcohol and amine and the derived benzyl, tert-butyl, or silyl ethers as well as various amides are particularly effective substrates; also suitable are a wide range of aryl-substituted terminal alkynes, where higher α-selectivity is achieved with substrates that bear an electron-withdrawing substituent. α-Selective Cu-catalyzed hydroborations are amenable to gram-scale procedures (1 mol % catalyst loading). Mechanistic studies are presented, indicating that α selectivity arises from the structural and electronic attributes of the NHC ligands and the alkyne substrates. Consistent with suggested hypotheses, catalytic reactions with a Cu complex, derived from an N-adamantyl-substituted imidazolinium salt, afford high β selectivity with the same class of substrates and under similar conditions.
Synthesis of functionalized vinyl boronates via ruthenium-catalyzed olefin cross-metathesis and subsequent conversion to vinyl halides
Morrill, Christie,Grubbs, Robert H.
, p. 6031 - 6034 (2007/10/03)
Functionalized vinyl pinacol boronates suitable for Suzuki cross-coupling reactions are synthesized using ruthenium-catalyzed olefin cross-metathesis of 1-propenyl pinacol boronate and various alkenes, including functionalized and 1,1-disubstituted alkenes. The resultant boronate cross products are stereoselectively transformed into predominantly Z-vinyl bromides and E-vinyl iodides. The vinyl bromides may be synthesized in a two-step, one-pot synthesis from a variety of olefins, resulting in a Z-selective formal vinyl bromide cross-metathesis reaction.
