Enantioselective Desymmetrization via Carbonyl-Directed Catalytic Asymmetric Hydroboration and Suzuki–Miyaura Cross-Coupling
摘要:
The rhodium-catalyzed enantioselective desymmetrization of symmetric gamma,delta-unsaturated amides via carbonyl-directed catalytic asymmetric hydroboration (directed CAHB) affords chiral secondary organoboronates with up to 98% ee. The chiral gamma-borylated products undergo palladium-catalyzed Suzuki-Miyaura cross-coupling via the trifluoroborate salt with stereoretention.
Mechanism-Based Design of an Amide-Directed Ni-Catalyzed Arylboration of Cyclopentene Derivatives
作者:Alison L. Lambright、Yanyao Liu、Isaac A. Joyner、Kaitlyn M. Logan、M. Kevin Brown
DOI:10.1021/acs.orglett.0c04208
日期:2021.1.15
arylboration of cyclopentenes is disclosed. The reaction allows for the synthesis of sterically congested cyclopentane scaffolds that contain an easily derivatized boronic ester and amide functional handles. The nature of the amide directing group and its influence on the reactionoutcome are investigated and ultimately reflect a predictably selective reaction based on the solvent and base counterion.
Desymmetrization of Prochiral Cyclopentenes Enabled by Enantioselective Palladium-Catalyzed Oxidative Heck Reaction
作者:Guihua Chen、Jian Cao、Qian Wang、Jieping Zhu
DOI:10.1021/acs.orglett.9b04357
日期:2020.1.3
catalytic amount of Pd(TFA)2 and a chiral Pyox ligand under oxygen atmosphere, oxidative Heck reaction between arylboronic acids and 4-substituted or 4,4-disubstituted cyclopent-1-enes afforded the chiral arylated products with concurrent creation of two stereocenters in good yields with excellent diastereo- and enantioselectivities.
nucleopalladation of alkynes have been developed into powerful synthetic tools for the synthesis of functionalized heterocycles. However, a catalytic enantioselective version of this class of reactions remains scarce. We report herein that reaction of 2‐alkynylanilines with prochiral cyclopentenes in the presence of a catalytic amount of Pd(OAc)2, a chiral bidentate pyrox ligand and O2 as terminal oxidant affords the
Excellent enantioselectivities (up to 97 % ee) and diastereoselectivities (up to >99:1 d.r.) have been achieved in the desymmetrization of cyclopentenes by catalytic hydroformylation. This novel methodology provides an efficient and concise synthetic route to chiral cyclopentane carboxaldehydes. The key intermediate, (1S,3S)‐(3‐hydroxymethyl)cyclopentanol, for the synthesis of carbocyclic‐ddA was obtained