Stereoselective Synthesis of Cyclohexanes via an Iridium Catalyzed (5 + 1) Annulation Strategy
作者:Wasim M. Akhtar、Roly J. Armstrong、James R. Frost、Neil G. Stevenson、Timothy J. Donohoe
DOI:10.1021/jacs.8b07776
日期:2018.9.26
An iridium catalyzed method for the synthesis of functionalized cyclohexanes from methyl ketones and 1,5-diols is described. This process operates by two sequential hydrogen borrowing reactions, providing direct access to multisubstituted cyclic products with high levels of stereocontrol. This methodology represents a novel (5 + 1) strategy for the stereoselective construction of the cyclohexane core
A Phosphine-Free Manganese Catalyst Enables Stereoselective Synthesis of (1 + <i>n</i>)-Membered Cycloalkanes from Methyl Ketones and 1,<i>n</i>-Diols
作者:Akash Jana、Kuhali Das、Abhishek Kundu、Pradip Ramdas Thorve、Debashis Adhikari、Biplab Maji
DOI:10.1021/acscatal.9b05567
日期:2020.2.21
Herein, we report the stereoselective synthesis of (1 + n)-membered cycloalkane from methyl ketone and 1,n-diol. A manganese(I) complex bearing a phosphine-free ligand catalyzed the reaction, which involved the formation of two C–C bonds via a sequence of intermolecular- and intramolecular-borrowing hydrogenation reactions. It produces 2 mol of water as the sole byproduct, making the process atom economical
Stereoselective synthesis of alicyclic ketones: A hydrogen borrowing approach
作者:Roly J. Armstrong、Wasim M. Akhtar、James R. Frost、Kirsten E. Christensen、Neil G. Stevenson、Timothy J. Donohoe
DOI:10.1016/j.tet.2019.130680
日期:2019.11
A highly diastereoselective annulation strategy for the synthesis of alicyclic ketones from diols and pentamethylacetophenone is described. This process is mediated by a commercially available iridium(III) catalyst, and provides efficient access to a wide range of cyclopentane and cyclohexane products with high levels of stereoselectivity. The origins of diastereoselectivity in the annulation reaction
highly efficient iridium-catalyzed asymmetric hydrogenation of racemic α-substituted lactones via dynamic kinetic resolution. Using Ir-SpiroPAP (R)-1d as a catalyst, a wide range of chiral diols were prepared in a high yield (80–95%) with a high enantioselectivity (up to 95% ee) under mild reaction conditions. This protocol was used for enantioselective syntheses of (−)-preclamol and a chiral 2,5-disubstituted