Highly efficient catalyticasymmetricClaisenrearrangements of O‐propargyl β‐ketoesters and O‐allyl β‐ketoesters have been accomplished under mild reaction conditions. In the presence of the chiral N,N′‐dioxide/NiII complex, a wide range of allenyl/allyl‐substituted all‐carbon quaternary β‐ketoesters was obtained in generally good yield (up to 99 %) and high diastereoselectivity (up to 99:1 d.r.)
O-炔丙基β-酮酸酯和O-烯丙基β-酮酸酯的高效催化不对称克莱森重排反应是在温和的反应条件下完成的。在存在手性N,N'-二氧化物/ Ni II配合物的情况下,通常以良好的收率(高达99%)和高的非对映选择性(高达90%)获得各种各样的烯丙基/烯丙基取代的全碳季β-酮酸酯。至99:1 dr)的对映选择性(高达99%ee)。
Metal-Free Catalytic Asymmetric Fluorination of Keto Esters Using a Combination of Hydrogen Fluoride (HF) and Oxidant: Experiment and Computation
作者:Roman Pluta、Patricia E. Krach、Luigi Cavallo、Laura Falivene、Magnus Rueping
DOI:10.1021/acscatal.7b03118
日期:2018.3.2
for the catalytic asymmetric fluorination has been developed. The catalyst was used in the asymmetric fluorination of carbonyl compounds, providing the products with a quaternary stereocenter with high enantioselectivities. Chiral hypervalent iodine difluoride intermediates were generated in situ by treatment of the catalyst with an oxidant and hydrogen fluoride as fluoride source. As such, the α-fluorination
new protocol for the direct two-electron oxidative Umpolung of alkali halidesalts is reported. This procedure, relying on the use of a commercially available sulfoxide as the oxidant, allows the electrophilichalogenation of carbonyl compounds as well as halolactonisation reactions to proceed from the corresponding sodium salts, at room temperature and under mild conditions.
Amine-Promoted <i>anti</i>-Markovnikov Addition of 1,3-Dicarbonyl Compounds with Terminal Alkynes under Rhenium Catalysis
作者:Masahito Murai、Erika Uemura、Kazuhiko Takai
DOI:10.1021/acscatal.8b01338
日期:2018.6.1
accelerate the intermolecular anti-Markovnikov addition of carbon nucleophiles to unactivated terminalalkynes. Using a combination of [ReBr(CO)3(thf)]2 and iPr2NEt, construction of cyclic all-carbon quaternary centers was achieved with various 1,3-ketoesters, diketones, and diesters with lower catalyst loading under milder conditions. The type of addition could be easily controlled by choice of additive
The enantioselective Claisenrearrangement of allenyl vinyl ethers was realized to access branched 1,3-dienyl-substituted all-carbon quaternary stereocenters using a NiII-N,N[prime or minute]-dioxide complex.
实现了烯基乙烯基醚的对映选择性克莱森重排,以使用Ni II - N,N [伯或分钟]-二氧化物络合物接近支链的1,3-二烯基取代的全碳季立体中心。