Preparation of Carboxylic Esters and Phosphoric Esters by the Activation of Alcohols
作者:Oyo Mitsunobu、Masahiko Eguchi
DOI:10.1246/bcsj.44.3427
日期:1971.12
phosphate gave ethyl p-tolyl hydrogen phosphate and di p-tolyl pyrophosphate. The reaction of alkyl N,N′-tetraethylphosphorodiamidites with carboxylic acids in the presence of diethyl azodicarboxylate resulted in the formation of corresponding carboxylicesters. When these reactions (benzoylation) were carried out with the use of optically active 2-octanol, 2-octyl benzoate was obtained with inverted
A highlyefficient majority‐rules effect of poly(quinoxaline‐2,3‐diyl)s (PQXs) bearing 2‐butoxymethyl chiral side chains at the 6‐ and 7‐positions was established and attributed to large ΔGh values (0.22–0.41 kJ mol−1), which are defined as the energy difference between P‐ and M‐helical conformations per chiral unit. A PQX copolymer prepared from a monomer derived from (R)‐2‐octanol (23 % ee) and a
Enantioselective Addition of Dimethylzinc to Aldehydes Catalyzed by a Chiral Perhydro-1,3-benzoxazine-Based Amino Alcohol as Ligand
作者:Javier Nieto、Celia Andrés、Rebeca Infante
DOI:10.1055/s-0031-1289742
日期:2012.5
undergoes efficient enantioselective addition to a wide variety of aromatic and aliphatic aldehydes in the presence of a catalytic amount of a chiral perhydro-1,3-benzoxazine-based aminoalcohol. Methyl carbinols are obtained in good yields and in enantiomeric excesses of 99% or more in the absence of any metal other than zinc. Dimethylzinc undergoes efficient enantioselective addition to a wide variety
Highly Enantioselective Rh-Catalysed Hydrogenation of 1-Alkyl Vinyl Esters Using Phosphine-Phosphoramidite Ligands
作者:Tina Maria Konrad、Pascal Schmitz、Walter Leitner、Giancarlo Franciò
DOI:10.1002/chem.201303066
日期:2013.9.27
MatPhos, a good mate for hard tasks: The asymmetric hydrogenation of 1‐alkyl vinyl esters, thwarted so far by mediocre ee values and low activities, can now be achieved with MatPhos/Rh catalysts with ee values of 96–99 % for a variety of substrates at low catalyst loadings (0.1–1 mol %) and under mild conditions (5–20 bar H2, room temperature). After hydrolysis, the corresponding chiral secondary alkyl
MatPhos,是完成艰苦任务的理想伴侣:迄今为止,由于中等ee值和低活性,阻碍了1-烷基乙烯基酯的不对称氢化,现在可以使用ee值为96–99%的MatPhos / Rh催化剂来实现在低催化剂负载量(0.1-1 mol%)和温和条件(5-20 bar H 2,室温)下制备底物。水解后,可以高对映体纯度获得相应的手性仲烷基醇,为获得这一重要产品类别提供了一条通用而实用的途径。
Synthesis of fluorous azodicarboxylates: towards cleaner Mitsunobu reactions
作者:Adrian P Dobbs、Caroline McGregor-Johnson
DOI:10.1016/s0040-4039(02)00322-2
日期:2002.4
The synthesis of a fluorous analogue of diethyl azodicarboxylate (DEAD) is described and preliminary results for its use in the Mitsunobureaction given. Use of fluorousextraction methods have shown that chromatography is not necessary for reactionpurification.