The highly efficient Ni-catalyzed asymmetric hydrogenation of β-boronic ester substituted-α,β-unsaturated carboxylic esters was successfully developed using (S,S)-Ph-BPE as the ligand. A series of chiral β-borylated carboxylic esters were obtained with high yields (94%–99% yields) and excellent enantioselectivities (89%–99% ee). The gram-scale asymmetric hydrogenation with a low catalyst loading (0
Copper(II)-Catalyzed β-Borylation of Acetylenic Esters in Water
作者:Webster Santos、Cheryl Peck、Joseph Calderone
DOI:10.1055/s-0034-1380524
日期:——
presence of bis(pinacolato)diboron and catalytic amounts of both copper(II) and 4-picoline, substituted alkynoates undergo borylation in a regio-, stereo-, and chemoselective fashion. The reaction is performed under mild conditions using water as solvent and open to the atmosphere to exclusively afford (Z)-β-boryl-α,β-unsaturated esters. A method for the β-borylation of alkynoates has been developed
Phosphine–copper(I) complexes efficiently catalyzed the mono-boration of electron-deficient alkynes in the presence of MeOH and also catalyzed conjugate reductions of alkenylboronates bearing an electron-withdrawing group. The mono-addition of bis(pinacolato)diboron to alkynes catalyzed by a copper–Xantphos complex produced vinylboronates with high regio and stereoselectivity and asymmetric reduction
Copper-catalyzed addition of diboron reagents to α,β-acetylenic esters: efficient synthesis of β-boryl-α,β-ethylenic esters
作者:Ji-Eon Lee、Jisook Kwon、Jaesook Yun
DOI:10.1039/b716697d
日期:——
The efficient copper-catalyzedaddition reaction of bis(pinacolato)diboron to alpha,beta-acetylenic esters has been developed, which produces the corresponding beta-borylated-alpha,beta-ethylenic esters in high yields under mild reaction conditions.
Trialkylphosphine organocatalysts have enabled regioselective anti-hydroboration of internal, alkynes with pinacolborane reagents to provide (E)-disubstituted alkenylboronate compounds. The alkenyl-boronate can be used for derivatizations, such as protodeborylation, Suzuld-Miyaura coupling, conjugate reduction, and Diels-Alder reactions.