A Chiral 6-Membered <i>N</i>-Heterocyclic Carbene Copper(I) Complex That Induces High Stereoselectivity
作者:Jin Kyoon Park、Hershel H. Lackey、Matthew D. Rexford、Kirill Kovnir、Michael Shatruk、D. Tyler McQuade
DOI:10.1021/ol1021756
日期:2010.11.5
A chiral 6-membered annulated N-heterocyclic (6-NHC) copper complex that catalyzes β-borylations with high yield and enantioselectivity was developed. The chiral 6-NHC copper complex is easy to prepare on the gram scale and is very active, showing 10 000 turnovers at 0.01 mol % of catalyst without significant decrease of enantioselectivity and with useful reaction rates.
Cyclic Iodine Reagents Enable Allylic Alcohols for Alkyl Boronate Addition/Rearrangement by Photoredox Catalysis
作者:Mingshang Liu、Hanchu Huang、Yiyun Chen
DOI:10.1002/cjoc.201800461
日期:2018.12
iodine(III) reagents enable the synthesis of cyclopentanones, cyclohexanones, and dihydrofuranones bearing α‐quaternary centers by photoredox catalysis. The reaction proceeds by the formation of the novel cyclic iodine(III) reagent‐allylic alcohol complex, which enables the first alkyl boronate addition and semi‐pinacol rearrangement of allylic alcohols with dual alcohol and olefin activation. The reaction
Combo effects: The first example of an iron‐mediated β‐boration of activated olefins is reported. The origin and the benefits of the catalytic activity associated with the presence of iron have been questioned and carefully studied. The iron system has been compared to the organocatalytic β‐boration of α,β‐unsaturated esters, ketones, and imines (see scheme; acac=acetylacetonate, pin=pinacol).
Addition and Coupling Reactions of Bis(pinacolato)diboron Mediated by CuCl in the Presence of Potassium Acetate
作者:Kou Takahashi、Tatsuo Ishiyama、Norio Miyaura
DOI:10.1246/cl.2000.982
日期:2000.9
The addition of bis(pinacolato)diboron [(Me4C2O2)B-B(O2C2Me4)] to α,β-unsaturated ketones, esters, nitriles, or terminal alkynes and the coupling with allyl chlorides were carried out in DMF at room temperature in the presence of CuCl and AcOK. The transmetalation from boron to copper generating a B–Cu species was proposed as the key step of the reactions.
Copper pins on the boron: The enantioselective 1,4‐addition of diboron to α,β‐unsaturatedcompounds proceeds smoothly in the presence of catalytic amounts of Cu(OH)2 and chiral 2,2′‐bipyridine ligand in water. A wide substrate scope of α,β‐unsaturatedcarbonylcompounds, including acyclic, cyclic, and β,β‐disubstituted enones, α,β‐unsaturated esters, amides, and a nitrile, has been shown.