Nickel/Photo-Cocatalyzed C(sp²)–H Allylation of Aldehydes and Formamides

Abstract

Herein we report a nickel/photo-cocatalyzed C­(sp2)–H allylation of aldehydes and formamides wherein both allyl acetates and allyl alcohols can be used as the allylating agents. In this reaction, radical-type umpolung of the formyl moiety is enabled by tetrabutylammonium decatungstate as a hydrogen-atom-transfer photocatalyst, whereas nickel serves to cleave the C–O bond of allyl acetates or allyl alcohols. The synergistic effect of these two catalysts provides new access to various β,γ-unsaturated ketones and amides with high selectivities.

Nickel/Photo-Cocatalyzed Asymmetric Acyl C–H Allylation of Aldehydes and Formamides

“…By synergistic merger of TBADT catalysis and transition metal catalysis, our group and others recently developed a set of reactions involving aldehydes as the acylating agent, such as olefin carbamoylacylation; acylation of aryl halides, benzyl chlorides, and Katritzky salts; dehydrogenative acylation of alkenes; and ring opening acylation of aziridines . Based on our previous study of the racemic version of acyl C–H allylation of aldehydes and formamides, we report in this context its first highly enantioselective variant providing a new entry to α-stereogenic β,γ-unsaturated 1,4-dicarbonyl compounds (Scheme C).…”

Nickel/Photo‐Cocatalyzed Acyl C−H Benzylation of Aldehydes with Benzyl Chlorides

“…[12] Subsequently, we successfully implemented the cooperative catalysis of TBADT and nickel in the cross-coupling reactions of aldehydes with aryl halides, [13] α-bromo acetates, [13] N-tosyl styrenyl aziridines, [14] as well as allyl acetates. [15] Very recently, a similar protocol describing the cross-coupling reaction of aldehydes with benzylic and allylic Katritzky salts via CÀ N bond cleavage was reported by Rasappan and coworkers. [16] As a part of our ongoing studies in this research field, we demonstrate herein the accomplishment of acyl CÀ H benzylation of aldehydes with primary and secondary benzyl chlorides under the cocatalysis of nickel and TBADT (Scheme 1B).…”

“…In 2020, we achieved the synergistic catalysis of TBADT and a chiral Ni‐PHOX complex for asymmetric acyl‐carbamoylation of carbamoyl chloride‐tethered alkenes with aldehydes [12] . Subsequently, we successfully implemented the cooperative catalysis of TBADT and nickel in the cross‐coupling reactions of aldehydes with aryl halides, [13] α ‐bromo acetates, [13] N ‐tosyl styrenyl aziridines, [14] as well as allyl acetates [15] . Very recently, a similar protocol describing the cross‐coupling reaction of aldehydes with benzylic and allylic Katritzky salts via C−N bond cleavage was reported by Rasappan and co‐workers [16] .…”

Synthesis of 1,4-diketones via palladium/photo-cocatalyzed dehydrogenative cross-coupling

“…hydroacylation of electron-deficient alkenes, 11 imines, 12 and diazo compounds, 13 acyl C–H fluorination, 14 alkynylation, 15 fluoromethyl-thiolation, 16 and deuteration. 17 Recently, under cooperative catalysis with transition metals including Ni, Pd, and Co, the scope of TBADT-catalyzed reactions using aldehydes has been expanded to acyl C–H arylation, 18 benzylation, 19 alkenylation, 20 allylation, 21 alkylation, 22 and aziridine ring opening. 23 As a continuation of our research work in TBADT-catalyzed acylation using aldehydes as the acyl source, 18 a ,19 b ,21–23 we envisioned a Pd/TBADT-cocatalyzed dehydrogenative cross-coupling reaction between allylic alcohols and aldehydes towards the synthesis of 1,4-diketones (Scheme 1B).…”