Asymmetric Retro-Claisen Reaction by Synergistic Chiral Primary Amine/Palladium Catalysis
作者:Yanfang Han、Long Zhang、Sanzhong Luo
DOI:10.1021/acs.orglett.9b02491
日期:2019.9.20
We described herein a chiral primaryamine/palladium catalyzed asymmetric retro-Claisen reaction of β-diketones with salicylic carbonates. A series of chiral α-alkylated ketones and macrolides were obtained with good yields and excellent enantioselectivities upon a sequence of decarboxylative benzylation, retro-Claisen cleavage, and enamine protonation. This strategy features broad substrate scope
Asymmetric Allylation of Unsymmetrical 1,3-Diketones Using a BINAP−Palladium Catalyst
作者:Ryoichi Kuwano、Kei-ichi Uchida、Yoshihiko Ito
DOI:10.1021/ol034665s
日期:2003.6.1
[reaction: see text] The chiral palladium complex generated in situ from [Pd(eta(3)-allyl)Cl](2) and (R)-BINAP is a good catalyst for the catalytic asymmetricallylation of 1,3-diketones. The reaction provided chiral 2,2-dialkyl-1,3-diketones with 64-89% ee in high yields (13 examples). Enantiomeric excesses are strongly affected by the gamma-substituent of the allylic substrates. A variety of unsymmetrical
presence of a catalytic amount of a rhenium or manganese complex gives ring‐expanded and carbon‐chain extension products, respectively. In these reactions, alkynes insert into a non‐strained carbon–carbonsinglebond of 1,3‐dicarbonyl compounds. The ring‐expansion reaction is also promoted by the addition of 4‐Å molecular sieves instead of a catalytic amount of an isocyanide.
Asymmetric Retro-Claisen Reaction by Chiral Primary Amine Catalysis
作者:Yunbo Zhu、Long Zhang、Sanzhong Luo
DOI:10.1021/jacs.6b00627
日期:2016.3.30
The communication describes an enamine-based asymmetric retro-Claisen reaction of β-diketones by primaryamine catalysis. The reaction proceeds via a sequence of stereoselective C-C formation, C-C cleavage, and a highly stereospecific enamine protonation to afford chiral α-alkylated ketones or macrolides with high yields and enantioselectivities. A detailed mechanism was explored on the basis of experimental
该通讯描述了伯胺催化下 β-二酮的基于烯胺的不对称逆克莱森反应。该反应通过一系列立体选择性 CC 形成、CC 裂解和高度立体有择的烯胺质子化进行,以提供具有高产率和对映选择性的手性 α-烷基化酮或大环内酯。在实验证据和计算研究的基础上探索了详细的机制,以解释观察到的立体控制。
Regiochemistry of the Reaction of 2-Acylcyclohexanones with Trimethyl Orthoformate: A Convenient One-Pot Method to Obtain 7,7-Dimethoxy Alkanoate Methyl Esters
作者:Marcos A. P. Martins、Giovani P. Bastos、Adilson P. Sinhorin、Alex F. C. Flores、Helio G. Bonacorso、Nilo Zanatta
DOI:10.1055/s-1999-2725
日期:1999.6
The regiochemistry of the reaction of 2-acylcyclohexanones [containing 2-acyl groups, C(O)R, where R = Me, Et, CH2Ph, CF3, Ph and OMe] with trimethyl orthoformate to obtain the corresponding acetal derivative is reported. Compounds with R = alkyl groups showed to be convenient synthons for a one-pot method to obtain 7,7-dimethoxy alkanoate methyl esters under mild conditions. The results of the reaction of 2-acetylcyclopentanone, -heptanone and -octanone with trimethyl orthoformate are also reported.