Methylation of amines and ketones with palladacycle precatalyst has been performed using methanol as an environmentally benign reagent. Various ketones and amines undergo methylation reaction to yield monomethylated amines or ketones in moderate to good isolated yields. Moreover, this protocol was tested for the chemoselective methylation of 4-aminobenzenesulfonamide. The scope of the reaction was
A chiral cyclohexadiene-based dihydrogen surrogate can distinguish between the enantiotopic faces of benzylic carbenium ions (see Scheme). No covalent interactions are required but instead dispersion controls the facial discrimination as verified by computations.
Synthesis of Ketones through Microwave Irradiation Promoted Metal-Free Alkylation of Aldehydes by Activation of C(sp<sup>3</sup>)–H Bond
作者:Xinying Zhang、Zhangxin Wang、Xuesen Fan、Jianji Wang
DOI:10.1021/acs.joc.5b01824
日期:2015.11.6
In this paper, a novel methodology for the synthesis of ketones via microwave irradiation promoted direct alkylation of aldehydes by activation of the inert C(sp(3))-H bond has been developed. Notably, the reactions were accomplished under metal-free conditions and used commercially available aldehydes and cycloalkanes as substrates without prefunctionalization. By using this novel method, an alternative synthetic approach toward the key intermediates for the preparation of the pharmaceutically valuable oxaspiroketone derivatives was successfully established.
Hydrogen-Borrowing and Interrupted-Hydrogen-Borrowing Reactions of Ketones and Methanol Catalyzed by Iridium
作者:Di Shen、Darren L. Poole、Camilla C. Shotton、Anne F. Kornahrens、Mark P. Healy、Timothy J. Donohoe
DOI:10.1002/anie.201410391
日期:2015.1.26
use of catalytic [Ir(cod)Cl}2] to facilitate hydrogen‐borrowing reactions of ketone enolates with methanol at 65 °C. An oxygen atmosphere accelerates the process, and when combined with the use of a bulky monodentate phosphine ligand, interrupts the catalytic cycle by preventing enone reduction. Subsequent addition of pro‐nucleophiles to the reaction mixture allowed a one‐pot methylenation/conjugate