Modular Access to Quaternary α-Hydroxyl Acetates by Catalytic Cross-Coupling of Alcohols

Abstract

Quaternary α-hydroxyl acids and their derivatives have attracted considerable attention because of their unique and broad functionalities. Herein, we successfully established a selective and modular protocol to access quaternary α-hydroxyl acetates via dehydrogenative cross-coupling of 1,2-diols and primary alcohols by using tris-N-heterocyclic carbene iridium (tris-NHC-Ir, 0.05 mol %) complexes as catalysts and Ba(OH)2 as the base, along with the generation of byproducts water and hydrogen gas. A plausible mechanism involving dehydrogenation of alcohols, aldol-condensation, and 1,2-alkyl rearrangement reactions was proposed, in which 1,2-alkyl rearrangement was responsible for the construction of the quaternary carbon center.

Manganese‐Catalyzed Mono‐N‐Methylation of Aliphatic Primary Amines without the Requirement of External High‐Hydrogen Pressure

“…Firstly, the kinetic isotope effect (KIE) of the reaction was measured. [24] The parallel experiment yielded a KIE value of 2.2, whereas the intermolecular competition KIE resulted in a slightly lower KIE value of 2.0. This indicates that dehydrogenation of methanol could be the rate-determining step (Figure S3-S4).…”

In situ exfoliation of a copper-based metal–organic framework for boosting the synergistic photoactivation of inert C(sp3)–H bonds and oxygen

“…13 Recently, by the elaborate decoration of binuclear copper nodes as HAT catalysts, a new 3D MOF containing photosensitizing NAD + mimic bridging linkers was obtained, which combined the high activity of chlorine radicals and the synergistic catalytic effect of LMCT, HAT, EnT and single electron transfer (SET) processes in the photocatalytic process to achieve inert C(sp 3 )-H bond oxidation. 23 However, 3D MOFs suffer from pore size limitation, slow electron communication and substrate diffusion, which limit their photocatalytic activity for the oxidation of inert C(sp 3 )-H bonds. 24,25 In the meantime, various twodimensional (2D) layered nano-sized catalytic materials possessing ultrathin thickness, such as metal oxides and hydroxides, 26 boron/carbon nitrides, 27 graphene and graphene oxides, 28 and transition metal dichalcogenides, 29 have been developed as a powerful strategy to improve catalytic conversion efficiency and shown surprising activity for photocatalytic activation and transformation in the last few decades, because their high surface areas and abundant readily accessible active sites enhance the communications between the catalytically active sites and substrate molecules and minimize the pathways associated with mass/charge transfer.…”

Environmentally Friendly Synthesis of Highly Substituted Phenols Using Enallenoates and Grignard Reagents

“…10 Over the past decade, significant research has been dedicated to synthesizing highly substituted phenolic compounds, achieving remarkable chemo-and regioselectivity. 11 This has often involved approaches like high-temperature isomerization or the use of transition-metal catalysis. Within the context of regioselective synthesis of substituted phenol, a commonly employed method involves the rearrangement of the aryl substituent into the neighboring ortho position at high temperatures (Scheme 1i).…”