Carbon quaternization of redox active esters and olefins by decarboxylative coupling.

The synthesis of quaternary carbons often requires numerous steps and complex conditions or harsh reagents that act on heavily engineered substrates. This is largely a consequence of conventional polar-bond retrosynthetic disconnections that in turn require multiple functional group interconversions, redox manipulations, and protecting group chemistry. Here, we report a simple catalyst and reductant combination that converts two types of feedstock chemicals, carboxylic acids and olefins, into tetrasubstituted carbons through quaternization of radical intermediates.

Alkene Hydrobenzylation by a Single Catalyst That Mediates Iterative Outer-Sphere Steps.

Cross-coupling catalysts typically react and unite functionally distinct partners via sequential inner-sphere elementary steps: coordination, migratory insertion, reductive elimination, etc. Here, we report a single catalyst that cross-couples styrenes and benzyl bromides via iterative outer-sphere steps: metal-ligand-carbon interactions. Each partner forms a stabilized radical intermediate, yet heterocoupled products predominate.

Iron-Catalyzed Hydrobenzylation: Stereoselective Synthesis of (-)-Eugenial C.

Metal-hydride hydrogen atom transfer (MHAT) has emerged as a useful tool to form quaternary carbons from alkenes via hydrofunctionalization. Methods to date that cross-couple alkenes with sp partners rely on heterobimetallic catalysis to merge the two cycles. Here, we report an iron-only cross-coupling via putative MHAT/S2 steps that solves a key stereochemical problem in the synthesis of meroterpenoid eugenial C and obviates the need for nickel.

Synthesis of chiral anti-1,2-diamine derivatives through copper(I)-catalyzed asymmetric α-addition of ketimines to aldimines.

Chiral 1,2-diamines serve as not only common structure units in bioactive molecules but also useful ligands for a range of catalytic asymmetric reactions. Here, we report a method to access anti-1,2-diamine derivatives. By means of the electron-withdrawing nature of 2- or 4-nitro-phenyl group, a copper(I)-catalyzed asymmetric α-addition of ketimines derived from trifluoroacetophenone and 2- or 4-NO-benzylamines to aldimines is achieved, which affords a series of chiral anti-1,2-diamine derivatives in moderate to high yields with moderate to high diastereoselectivity and high to excellent enantioselectivity.

Asymmetric Borylative Propargylation of Ketones Catalyzed by a Copper(I) Complex.

A copper(I)-catalyzed asymmetric borylative propargylation of simple ketones was disclosed. Additive NaBARF was found to be pivotal to achieve excellent enantioselectivity. This reaction enjoyed advantages of broad substrate scope, good tolerance of functional groups, high diastereo- and enantioselectivities, and reaction robustness.

Asymmetric Construction of Fluoroalkyl Tertiary Alcohols through a Three-Component Reaction of (Bpin), 1,3-Enynes, and Fluoroalkyl Ketones Catalyzed by a Copper(I) Complex.

An asymmetric three-component reaction of Bis(pinacolato)diboron ((BPin)), 1,3-enynes, and fluoroalkyl ketones was carried out by using a copper(I)-Ph-BPE complex as the catalyst, which afforded a series of chiral fluoroalkyl diols in good to high yield, good to high diastereoselectivity, and high enantioselectivity after an oxidative workup. The reaction exhibits advantages that include a broad substrate scope, high functional group compatibility, high stereoselectivity, and an easy reaction protocol. The synthetic utility of the reaction was showcased by several transformations.