Metal Free, Direct and Selective Deoxygenation of α‐Hydroxy Carbonyl Compounds: Access to α,α‐Diaryl Carbonyl Compounds

Abstract

An efficient, metal free, direct and selective deoxygenation of α-hydroxy carbonyl compounds is achieved with the aid of catalytic amount of aqueous HClO 4 (70 %) and triethylsilane as hydride source. A variety of α-hydroxy-α,α-diaryl carbonyl compounds are selectively deoxygenated to give α,α-[a]

Acidic Ionic Liquids as Metal-Free and Recyclable Catalysts for Direct Reduction of Aromatic Allylic Alcohol in Dimethyl Carbonate via Hydrogen Transfer

“…With the increasing demand for chemical sustainability and friendliness, developing a metal-free and recyclable catalytic system is becoming more attractive to reduce the use of toxic and expensive metals and benefits environmental compatibility, high efficiency, and so on. − To date, only several metal-free catalytic systems for direct deoxygenation of alcohols have been explored in halogen or supercritical media (Scheme c). − However, toxic halogens and harsh conditions prevented these systems from being widely used. In addition, our group developed TsOH·H 2 O as the Brønsted acid catalyst for direct reduction of aromatic allylic alcohols in toluene recently, providing up to 94% yield .…”

Conformational preferences in a series of α-hydroxy ketone derivatives: interplay of conformational energies and lattice cohesive energies

“…[27][28][29][30][31][32][33] In the past decade or so, tertiary α-hydroxy ketones have also been utilized as versatile building blocks to access biologically active scaffolds of heterocycles and α-functionalized ketones. [34][35][36][37][38][39][40] Analyses of the existence of conformational preferences (if any) among tertiary α-hydroxy ketone moieties may show some light on their mode of action (based on molecular topology) that leads to biological activity.…”

Destabilized Carbocations Caged in Water Microdroplets: Isolation and Real-Time Detection of α-Carbonyl Cation Intermediates

“…On the other hand, α-functionalization through α-carbonyl cations has recently emerged as an alternative to the enolate chemistry. Several synthetic strategies involving α-carbonyl cations have been developed in the past decade to achieve the α-functionalization of a wide variety of carbonyl compounds. − In all such conversions, though the intermediacy of α-carbonyl cations was proposed unequivocally, no favorable attempts could be made to capture and detect those elusive intermediates directly (Supplementary Note 1). α-Carbonyl cations are generally regarded as destabilized carbocations due to the presence of the electron-withdrawing carbonyl group at the cationic center. , Owing to its high reactivity toward the nucleophile or rapid molecular rearrangement, − intercepting and detecting an intrinsically unstable α-carbonyl cation from an ongoing reaction poses a challenging task.…”

“…We investigated the possible intermediacy of α-carbonyl cation in three model reactions: Friedel–Crafts arylation, deoxygenation, and azidation of α-hydroxy carbonyl compounds (Figure ). Based on substrate and product studies, literature precedence suggested the cleavage of the C–OH bond of the α-hydroxy carbonyl compound, forming the α-carbonyl cation as the key intermediate in mechanistic pathways of these reactions (Figure ).…”

“…In another set of experiments, we followed metal-free deoxygenation of α-hydroxy carbonyl compounds that we developed recently (Figure b) . The reaction was performed using a catalytic amount of aqueous perchloric acid and triethylsilane as the hydride source.…”