Pd-Catalyzed Acyl C–O Bond Activation for Selective Ring-Opening of α-Methylene-β-lactones with Amines
摘要:
A Pd-catalyzed ring-opening of beta-lactones with various types of amines (primary, secondary, and aryl) to provide beta-hydroxy amides with excellent selectivity toward acyl C-O bond cleavage is reported. The utility of this protocol is demonstrated in an asymmetric kinetic resolution providing enantioenriched a-methylene-beta-lactones.
2<i>H</i>-Chromene-3-carboxylic Acid Synthesis via Solvent-Controlled and Rhodium(III)-Catalyzed Redox-Neutral C–H Activation/[3 + 3] Annulation Cascade
作者:Zhi Zhou、Mengyao Bian、Lixin Zhao、Hui Gao、Junjun Huang、Xiawen Liu、Xiyong Yu、Xingwei Li、Wei Yi
DOI:10.1021/acs.orglett.8b01477
日期:2018.7.6
redox-neutral synthesis of 2H-chromene-3-carboxylic acids from N-phenoxyacetamides and methyleneoxetanones has been realized via a solvent-controlled and rhodium(III)-catalyzed C–H activation/unusual [3 + 3] annulation sequence. This transformation represents the first example of using an α-methylene-β-lactone unit as the three-carbon source in transition-metal-catalyzed C–H activationsthroughselective alkyl
polarity and revealing expanded reactivity patterns. Through this analysis formalism, polarity matching has been established for Rh(III)-catalyzed N-amino-directed C–H coupling with 3-methyleneoxetan-2-ones, providing efficient access to 1,2-dihydroquinoline-3-carboxylic acids. The identified reaction, by virtue of the internal oxidative mechanism, showcases mild reaction conditions (room temperature),