Esterification of the Primary Benzylic C–H Bonds with Carboxylic Acids Catalyzed by Ionic Iron(III) Complexes Containing an Imidazolinium Cation
作者:Bing Lu、Fan Zhu、Hong-Mei Sun、Qi Shen
DOI:10.1021/acs.orglett.7b00148
日期:2017.3.3
The first iron-catalyzedesterification of the primary benzylic C–H bonds with carboxylic acids using di-tert-butyl peroxide as an oxidant is achieved by novel ionic iron(III) complexes containing an imidazolinium cation. The use of well-defined, air-stable, and available iron(III) complex in a 5 mol % loading and readily available starting materials with a broad generality and outstanding sterically
A Relative Organolithium Stability Scale Derived from Tin−Lithium Exchange Equilibria. Substituent Effects on the Stability of α-Oxy- and α-Aminoorganolithium Compounds
作者:Paula Graña、M. Rita Paleo、F. Javier Sardina
DOI:10.1021/ja025552r
日期:2002.10.1
Quantitative thermodynamic stability scales of organolithiumcompounds can be derived from measurements of tin−lithium exchange equilibria. A ΔGeq scale of α-oxy- and α-aminoorganolithium compounds was established, and quantitative stabilization effects of O-alkyl, O-alkoxyalkyl, O-carbamoyl, N-carbamoyl, and O-carbonyl groups of the α-carbanion are presented. It has been found that an α-oxycarbanion
有机锂化合物的定量热力学稳定性标度可以从锡-锂交换平衡的测量中推导出来。建立了α-氧基-和α-氨基有机锂化合物的ΔGeq标度,并给出了α-碳负离子的O-烷基、O-烷氧基烷基、O-氨基甲酰基、N-氨基甲酰基和O-羰基的定量稳定作用。已经发现,α-氧碳负离子通过作为 O-取代基的羰基比通过烷基或烷氧基烷基更好地稳定,而不同的 O-羰基取代基的阴离子稳定效果是可比的。发现 N-氨基甲酰基比其 O-氨基甲酰基对应物具有更高的稳定作用。提供的 NMR 数据表明,苄基 N 或 O 取代的碳负离子具有高度平面化的结构,其中负电荷高度离域。从锡-锂交换中获得的稳定性数据可以轻松转换为“有效 pK”数据,这些数据可用于预测酸...
Enantioselective synthesis of α-phenyl- and α-(dimethylphenylsilyl)alkylboronic esters by ligand mediated stereoinductive reagent-controlled homologation using configurationally labile carbenoids
作者:Adam L. Barsamian、Zhenhua Wu、Paul R. Blakemore
DOI:10.1039/c5ob00159e
日期:——
with a combination of O-(α-lithiobenzyl)-N,N-diisopropylcarbamate and ligand 3,3-bis[(4S)-4,5-dihydro-4-isopropyloxazol-2-yl] pentane in toluene solvent (−78 °C to rt) with MgBr2·OEt2 additive. Enantioenrichedα-(dimethylsilylphenylsilyl)alkylboronates were obtained in 35–69% yield and 9–57% ee by reaction of B-alkyl pinacol boronates with a combination of lithio(dimethylphenylsilyl)methyl 2,4,6-triisopropylbenzoate