Efficient and Sustainable One‐pot Synthesis of α‐Carbonyl Homoallylic Alcohols from Benzaldehyde and Allylic Alcohols Using both NHC and Nickel Catalysts

Abstract

α‐carbonyl homoallylic alcohols have been synthesized in a one‐pot reaction from benzaldehyde and allylic alcohols. The nickel‐catalyzed allylation of α‐hydroxyketones has first been studied and allowed the identification of Ni(cod)2/dppf as the most suitable catalytic system. The tandem reaction that combines the benzoin condensation of aldehydes (synthesis of α‐hydroxyketones) promoted by the 1,3‐dimethylimidazolium chloride/DBU system and the nickel‐catalyzed allylic alkylation with allylic alcohol has been realized in EtOH as green solvent. The reaction is 100 % atom‐economical and water is formed as sole by‐product. A broad scope of different benzaldehyde derivatives as well as various allylic alcohols is also described.

Direct Synthesis of Gem-β,β′-Bis(alkyl) Alcohols Using Nickel Catalysis via Sequential DCR Approach

“…Unfortunately, the selective synthesis of β,β-disubstituted branched alcohols was not successful . We have realized that synthesis of β,β-disubstituted branched alcohols is associated with a few key challenges: (i) a mixture of undesired ketones and vital selectivity issues and (ii) the formation of self-aldol products along with undesired side products (Scheme b) …”

Nickel-Catalyzed Ligand-Controlled Regioselective Allylic Alkenylation of Allylic Alcohols with Easily Accessible Alkenyl Boronates: Synthesis of 1,4-Dienes

“…This is followed by reductive elimination at the less sterically congested C1-position to deliver the desired products. Alternatively, the direct oxidative addition of allylic alcohol to nickel(0) complex is also plausible according to the related reports on nickel-catalyzed direct substitution of allylic alcohols. ,,− …”

“…In this context, allylic substitution utilization of nickel as the catalyst has been proven to be a promising method due to the easy oxidative addition of allylic alcohols to nickel(0) species. For example, the coupling of allylic alcohols with organometallic reagents such as magnesium, boron, zinc, and silyl-metal reagents and nonmetallic compounds such as aldehyde/ketones, benzyl nitriles, amines, or amides has been achieved under nickel catalysis. On the other hand, 1,4-dienes are widely present in biologically active substances and pharmaceuticals (Figure ).…”