Photoinduced Gold-Catalyzed Domino C(sp) Arylation/Oxyarylation of TMS-Terminated Alkynols with Arenediazonium Salts

Abstract

A selective and convenient synthesis of tri- and tetrasubstituted α,β-unsaturated ketones, as well as 2,3-diarylbenzofurans has been developed with the aid of light and taking advantage of a cooperative gold/photoredox-catalyzed 2-fold arylation reaction of TMS-terminated alkynols. The reaction of 3-(trimethylsilyl)prop-2-yn-1-ols was competent to generate diarylated α,β-unsaturated ketones; whereas the photoredox sequence involving 2-[(trimethylsilyl)ethynyl]phenol exclusively afforded 2,3-diarylbenzofurans. The reaction of terminal alkynes proceeded in poor yields while the use of bulkier silyl groups, such as TIPS, resulted unproductive. Apparently, the C(sp) arylation reaction is the first event on the domino bis-arylative sequence. These results could be explained through the intermediation of arylgold(III) species and several single electron transfer processes.

Gold‐Catalyzed Cross‐Coupling Reactions: An Overview of Design Strategies, Mechanistic Studies, and Applications

“…[269] Under the same reaction conditions, 2-[(trimethylsilyl)ethynyl]phenol could be convertedt o2,3-diarylbenzofurans. [269] Under the same reaction conditions, 2-[(trimethylsilyl)ethynyl]phenol could be convertedt o2,3-diarylbenzofurans.…”

“…Fouquet et al and Gauchot and Scheme51. Dual Au and photoredox catalyzedbis-arylative C(sp)ÀC(sp 2 ) bond-forming cross-coupling reactionsi nvestigated by (a-e) Alcaide et al [269,270] and (f) Wang et al [271] Scheme53. Dual Au and photoredox catalyzedbis-arylative C(sp)ÀC(sp 2 ) bond-forming cross-coupling reactionsi nvestigated by (a-e) Alcaide et al [269,270] and (f) Wang et al [271] Scheme53.…”

“… Dual Au and photoredox catalyzed bis‐arylative C(sp)−C(sp 2 ) bond‐forming cross‐coupling reactions investigated by (a–e) Alcaide et al . and (f) Wang et al …”

Insights into the Mechanism of Gold(I) Oxidation with Aryldiazonium Salts

“…Startingf rom TMS-terminated alkynols, Alcaide, Almendros, and co-workers were able to describe ab isarylation protocol, by using ad omino Hiyama-Sonogashira-type coupling/arylative Meyer-Schuster rearrangement (Scheme 11 b). [34] Unlike previously reported Meyer-Schuster/arylation protocols (Schemes 6c and 7), [22,23,24] in this protocolt wo aryl units where introduced in one-pot with the possibility that the two aryl moieties can be different. In this way,t hey could synthesized diarylated a,b-unsaturated ketones startingf rom 3-(trimethylsilyl)prop-2-yn-1-ols and 2,3-diarylbenzofurans starting from 2-[(trimethylsilyl)ethynyl]phenol.…”

Recent Advances in Photoredox Methods for Ketone Synthesis

“…A convenient approach for the synthesis of tri‐ and tetra‐substituted α,β‐unsaturated ketones using gold/photo redox dual catalytic approach was reported by Lazaro‐Milla and co‐workers (Scheme ) . The protocol demonstrates the C(sp)‐arylation/oxyarylation of trimethylsilyl (TMS)‐terminated alkynols when reacted with arenediazonium salts under the synergistic effect of gold catalysis and ruthenium mediated photocatalysis.…”