Lewis Base-Promoted Ring-Opening 1,3-Dioxygenation of Unactivated Cyclopropanes Using a Hypervalent Iodine Reagent
作者:Matthew H. Gieuw、Zhihai Ke、Ying-Yeung Yeung
DOI:10.1002/anie.201713422
日期:2018.3.26
A facile and effective system has been developed for the regio‐ and chemoselective ring‐opening/electrophilic functionalization of cyclopropanes through C−C bond activation by [bis(trifluoroacetoxy)iodo]benzene with the aid of the Lewis basic promoter p‐toluenesulfonamide. The p‐toluenesulfonamide‐promoted system works well for a wide range of cyclopropanes, resulting in the formation of 1,3‐diol products
Highly Diastereofacial <i>Anti</i>-Aldol Reaction: Practical Synthesis of Optically Active <i>anti</i>-2-Alkyl-3-Hydroxycarboxylic Acid Ester Units
作者:Michio Kurosu、Miguel Lorca
DOI:10.1021/jo001293h
日期:2001.2.1
variety of esters derived from commercially available norephedrine were used in diastereoselective anti-aldol reactions. The aldolreaction of designed 2-(N-2-methylbenzyl-N-2,4,6-trimethylbenzyl)amino-1-phenylpropanol esters 4a-d with aldehydes furnished anti-2-alkyl-3-hydroxycarboxylic acid esters in excellent diastereomeric ratios (>98:2) when LDA-Cp2ZrCl2 (0.3 equiv) was used for enolization, followed
Asymmetric catalysis. Production of chiral diols by enantioselective catalytic intramolecular hydrosilation of olefins
作者:Steven H. Bergens、Pedro Noheda、John Whelan、B. Bosnich
DOI:10.1021/ja00032a028
日期:1992.3
Rhodium(I) chiral diphosphine complexes efficiently and rapidly catalyze the intramolecular hydrosilation of silylethers derived fromallylicalcohols. The efficiency and rates of intramolecular hydrosilations were determined for a variety of silyl and olefin substituents. The catalysts were found to tolerate a widevariety of silyl substituents, although terminal alkyl olefin substituents were found to
Asymmetric synthesis using diisopropyl tartrate modified (E)- and (Z)-crotylboronates: preparation of the chiral crotylboronates and reactions with achiral aldehydes
作者:William R. Roush、Kaori Ando、Daniel B. Powers、Alan D. Palkowitz、Ronald L. Halterman
DOI:10.1021/ja00173a023
日期:1990.8
Crotylboronates undergo highly diastereo- and enantioselective reactions with aliphatic (linear or α-monobranched; 72-91% ee), aromatic and α,β-unsaturated aldehydes (55-74% ee). The reaction diastereoselectivity closely parallels the reagent isomeric purity especially for reactions performed at −78 o C. The enantioselectivity is best in toluene for all substrates except benzaldehyde where best results
巴豆基硼酸酯与脂肪族(线性或 α-单支链;72-91% ee)、芳香族和 α,β-不饱和醛(55-74% ee)发生高度非对映选择性和对映选择性反应。反应的非对映选择性与试剂异构体纯度密切相关,特别是对于在 -78 o C 下进行的反应。对所有底物的对映选择性在甲苯中最佳,但苯甲醛除外,因为苯甲醛在 THF 中获得最佳结果。本研究中合成的 14 种高烯丙醇中有 9 种的相对和绝对立体化学是通过与 Sharpless 不对称环氧化制备的环氧醇的相关性来确定的
The Direct, Enantioselective, One-Pot, Three-Component, Cross-Mannich Reaction of Aldehydes: The Reason for the Higher Reactivity of Aldimineversus Aldehyde in Proline-Mediated Mannich and Aldol Reactions
In the proline-mediatedMannich and aldolreactions of propanal as a nucleophile, the aldimine prepared from benzaldehyde and p-anisidine is about 7 times more reactive than the corresponding aldehyde, benzaldehyde, as an electrophile. This higherreactivity of aldimine over aldehyde is attributed to the carboxylic acid of proline protonating the basic nitrogen atom of the aldimine more effectively