An enantioselective intramolecular oxidative cyclization of 4-alkenoic acids was developed. The reaction proceeded via a π-allyl Pd intermediate generated by an allylic C–H activation to give γ-lactone derivatives with moderate to good enantioselectivity. Spiro bis(isoxazoline) ligand, SPRIX, was indispensable for this asymmetric transformation.
Enantioselectivebromolactonization of trisubstituted olefinicacids producing synthetically useful chiral lactones with two contiguous asymmetric centers has remained mainly unexplored except for the 6‐exo cyclization mode. In this work, the 5‐exo‐ and 6‐endo modes of bromocyclization of trisubstituted olefinicacids were enabled for the first time using N‐bromosuccinimide and a pyridyl phosphoramide
Cobalt-Catalyzed Hydrocyanation of Methylenecyclopropanes to Homoallylic Nitriles
作者:Mingdong Jiao、Xianjie Fang
DOI:10.1021/acs.orglett.2c03726
日期:2022.12.9
We describe herein a novel synthesis of various homoallylic nitriles via cobalt-catalyzed hydrocyanation of methylenecyclopropanes. Excellent selectivity, mild reaction conditions, good functional group compatibility, gram-scale reaction, and product transformations demonstrate the power of this protocol. This extraordinary selectivity can probably be attributed to the stronger aptitude of the alkyl–cobalt
Synthesis of Borylated Carbocycles by [2 + 2]-Cycloadditions and Photo-Ene Reactions
作者:Jarett M. Posz、Neetu Sharma、Paige A. Royalty、Yanyao Liu、Christophe Salome、Thomas C. Fessard、M. Kevin Brown
DOI:10.1021/jacs.4c01557
日期:2024.4.10
agrochemicals and pharmaceuticals. Here, we present the synthesis of borylated bicyclo[2.1.1]hexanes via crossed [2 + 2]-cycloaddition. Due to the presence of the C–B bond, a variety of structures can be easily prepared that are not accessible by other methods. Moreover, a rare photo-ene reaction is also disclosed, allowing for the diastereoselective synthesis of trisubstituted borylated cyclopentanes.
A dual bio-/photocatalytic system has been developed for achieving previously elusive diastereo- and enantioselective radical lactonizations. By integrating directed evolution and photoinduced single-electron oxidation, we repurposed engineered ene-reductases to steer non-natural radical C−O formations giving a diverse array of enantioenhanced 5- and 6-membered lactones with vicinal stereocenters,