<i>S</i>-((Phenylsulfonyl)difluoromethyl)thiophenium Salts: Carbon-Selective Electrophilic Difluoromethylation of β-Ketoesters, β-Diketones, and Dicyanoalkylidenes
S‐((Phenylsulfonyl)difluoromethyl)thiopheniumsalts were designed and prepared by a triflic acid catalyzed intramolecular cyclization of ortho‐ethynyl aryldifluoromethyl sulfanes. The thiopheniumsalts were found to be efficient as electrophilic difluoromehtylating reagents for introduction of a CF2H group to sp3‐hybridized carbon nucleophiles such as of β‐ketoesters and dicyanoalkylidenes. The (p
S -((苯磺酰基)二氟甲基)噻吩盐是通过三氟甲磺酸催化邻乙炔基芳基二氟甲基硫烷的分子内环化反应而设计和制备的。发现噻吩盐作为将CF 2 H基团引入sp 3杂交的碳亲核试剂(如β-酮酸酯和二氰基亚烷基)的亲电子二氟甲基化试剂非常有效。的(苯磺酰基)二氟甲基可容易地转化为CF 2温和反应条件下小时。在双(金鸡纳)生物碱的存在下也实现了对映选择性亲电二氟甲基化。
Cu(I)-catalyzed asymmetric α-hydroxylation of β-keto esters in the presence of chiral phosphine-Schiff base-type ligands
作者:Jia-Jun Jiang、Jian Huang、De Wang、Mei-Xin Zhao、Fei-Jun Wang、Min Shi
DOI:10.1016/j.tetasy.2010.05.011
日期:2010.4
Chiralphosphine-Schiff base-type ligand L1 prepared from (R)-(−)-2-(diphenylphosphino)-1,1′-binaphthyl-2′-amine was found to be a fairly effective ligand for Cu(I)-promoted enantioselective α-hydroxylation of β-ketoesters using oxaziridine 2a as the oxidant to give the corresponding products in high yields along with moderate enantioselectivities.
Bifunctional chiral thioureas have been successfully used as organocatalysts in enantioselectivefluorinations of β-ketoesters. The corresponding products could be obtained with good to excellent enantioselectivity in high yields by using N-fluorobisbenzenesulphonimide (NFSI) as fluorination reagent.
Enantioselective fluorination of β-ketoesters catalysed by complexes of new mono-oxazoline ligands
作者:Teng Niu、Xiping Han、Danfeng Huang、Ke-Hu Wang、Yingpeng Su、Yulai Hu、Ying Fu
DOI:10.1016/j.jfluchem.2015.02.017
日期:2015.7
A new kind of mono-oxazoline ligands which combined diaryl methyl units and chiral oxazoline units together using pyridine as linker was prepared. Their applications in enantioselective electrophilic fluorination of beta-ketoesters by NFSI were investigated, and the corresponding products were obtained in excellent yield (up to 90%) and good enantioselectivity (78%) in CH2Cl2 at -60 degrees C. (C) 2015 Elsevier B.V. All rights reserved.