16020-86-3

Upstream product

• 93-55-0 1-phenyl-propan-1-one 
• 925-90-6 ethylmagnesium bromide 
• 134-81-6 benzil 
• 20177-86-0 2-(1-methyl-2-oxo-2-phenylethylsulfanyl)-1-phenyl-propan-1-one 

Relevant academic research and scientific papers

Light-enabled metal-free pinacol coupling by hydrazine

Efficient carbon-carbon bond formation is of great importance in modern organic synthetic chemistry. The pinacol coupling discovered over a century ago is still one of the most efficient coupling reactions to build the C-C bond in one step. However, traditional pinacol coupling often requires over-stoichiometric amounts of active metals as reductants, causing long-lasting metal waste issues and sustainability concerns. A great scientific challenge is to design a metal-free approach to the pinacol coupling reaction. Herein, we describe a light-driven pinacol coupling protocol without use of any metals, but with N2H4, used as a clean non-metallic hydrogen-atom-transfer (HAT) reductant. In this transformation, only traceless non-toxic N2 and H2 gases were produced as by-products with a relatively broad aromatic ketone scope and good functional group tolerance. A combined experimental and computational investigation of the mechanism suggests that this novel pinacol coupling reaction proceeds via a HAT process between photo-excited ketone and N2H4, instead of the common single-electron-transfer (SET) process for metal reductants.

Photoredox-Catalyzed Reductive Coupling of Aldehydes, Ketones, and Imines with Visible Light

Ketyl radical and amino radical anions, valuable reactive intermediates for C-C bond-forming reactions, are accessible through a C=O/C=NR umpolung. However, their utilization in catalysis remains largely underdeveloped owing to the high reduction potential of carbonyl compounds and imines. In the context of photoredox catalysis, tertiary amines are commonly employed as sacrificial co-reducing agents. Herein, an additional role of the amine is proposed, in which it is essential for the organocatalytic substrate activation. The combination of photoredox catalysis and carbonyl/imine activation enables the reductive coupling of aldehydes, ketones, and imines under mild reaction conditions.

Electrochemical pinacol coupling of aromatic carbonyl compounds in a [BMIM][BF4]-H2O mixture

The electrochemical pinacol coupling reactions of aromatic carbonyl compounds were carried out using an 80% [BMIM][BF4]-H2O mixture as the electrolytic medium. The corresponding diols were obtained in good to excellent yields with moderate diastereoselectivity. The stereoselectivity can be explained using the strongly-bound ion-pairs formed between the imidazolium cation and the radical anions of the carbonyl compounds. The ionic liquid replaces both organic solvents and supporting electrolytes generally used in the electrosynthetic method. The electrolytic medium can be recycled and successfully reused at least in five consecutive reactions.

Iron-catalyzed pinacol coupling of aryl ketones with a phenyltitanium reagent: A new type of catalytic reaction

A reaction of aryl ketones with phenyltitanium triisopropoxide ([PhTi(Oi-Pr)3]) in the presence of [Fe(acac)3] as a catalyst (1 mol%) gave the corresponding pinacols in high yields. The catalytic cycle of this process involves an iron-catalyzed disproportionation of [PhTi(Oi-Pr) 3] into biphenyl and a lowvalent titanium species.

Efficient method for the preparation of pinacols derived from aromatic and aliphatic ketones by using low-valent titanium reagents in dichloromethane-pivalonitrile

The reductive coupling reaction of aldehydes and ketones, including unsymmetrical aliphatic ketones, proceeded smoothly to give the corresponding pinacols in good to high yields under mild conditions by using combination of titanium(II) chloride and zinc or titanium(IV) chloride and zinc in dichloromethane-pivalonitrile. Meso-selective formation of the coupling products was observed in the cases of some aliphatic ketones. The diastereoselectivities of coupling products depend on both difference of bulkiness of 2-, and 2'-substituents of carbonyl group of the reactant, and overall steric effect around the carbonyl groups.

STEREOSELECTIVE SYNTHESIS OF ERYTHRO- AND THREO-1,2-DIOLS FROM DIKETO SULFIDES VIA CIS-3,4-DIHYDROXYTHIOLANES

Intramolecular reductive coupling reaction of a series of diketo sulfides (1) by a low-valent titanium reagent at 0 deg C in tetrahydrofuran leads to cis-3,4-dihydroxythiolanes (2) exclusively in 67-89percent yields.Desulfurization of 2 by Raney nickel in

Reduction of Aromatic Carbonyl Compounds Promoted by Titanium Trichloride in Basic Media. Stereochemistry Studies

Aromatic ketones, which are not affected by Ti(III) chloride in acidic medium, react smoothly in basic media to afford the reductively coupled products according to the increase of the reducing power of Ti(III) ion with increasing pH.Benzil, benzoin, and methoxybenzoin give the corresponding alcohols.The observed stereochemistry is discussed in terms of intermolecular Ti bridging control (dl > meso) when intramolecular Ti complexation is prevented and in terms of steric control (meso > dl) when two sites of potential Ti complexation are available in the molecule.Thereagent, Ti(III) chloride, is selective in that many other functional groups are unaffected by it.

Studies on the Occurrence of Hydrogen Transfer, 73. - The Reduction of Prochiral Alkyl (Aryl) Ketones with Alkali Metal Amalgams Forming Carbinols and Pinakols

The factors are determined which influence the stereochemistry and the ratio (C/P) in the reduction of acetophenone with lithium, sodium, and potassium amalgam (Li/Hg, Na/Hg, K/Hg) leading to carbinol (C) and pinacol(P).The C/P ratio is influenced a) by proton donators, b) by quaternaryammonium salts, c) by bis-tertiary amines.In the presence of optically active quaternary ammonium salts and optically active bis-tertiary amines a low optical induction is observed both in pinacol and carbinol.An anomal dimerization product 20 is formed in the reduction of pivalophenone with Li/Hg.