Visible Light-Mediated Photocatalytic Metal-Free Cross-Coupling Reaction of Alkenyl Carboxylic Acids with Diarylphosphine Oxides Leading to β-Ketophosphine Oxides

Abstract

A new visible light-mediated photocatalytic decarboxylative oxyphosphorylation of cinnamic acids with diarylphosphine oxides is described. This reaction is performed under mild conditions to afford the corresponding β-ketophosphine oxides.

Visible light-mediated C P bond formation reactions

“…In 2016, Cai and co-workers [45] reported the first example of b-ketophosphine oxides synthesis via visible light-promoted oxidative phosphinylation of aryl alkynes. Two years later, Zou and co-workers [46] demonstrated an alternative photocatalytic method for b-ketophosphine oxides synthesis (Scheme 5). In this contribution, the cheap Rose Bengal (RB) is used as photoredox catalyst and a variety of cinnamic acids were applied as the phosphorus-centered radical acceptors.…”

Visible‐Light Mediated Photooxidative Synthesis of α‐Keto Amides

“…In addition, the standard reaction was performed in the presence of TEMPO (2.0 equiv. ), [39] which significantly decreased the yield of 3 a, indicating a radical pathway. Unfortunately, we did not notice any radical intermediate with TEMPO.…”

Metal‐Free Decarboxylation of α,β‐Unsaturated Carboxylic Acids for Carbon–Carbon and Carbon–Heteroatom Coupling Reactions

“…The desired product could be generated in DMSO at 40 o C under air for 24 h (Scheme 41a). [74] Han and co‐workers described the synthesis of ( E )‐alkenylphosphine oxides via a transition metal‐ free phosphorylation of cinnamic acids with P(O)H compounds. This reaction needs two equiv of TBPB as oxidant, K 2 HPO 4 as base and 5 mol% KI as catalyst, and proceeds smoothly in DMSO at room temperature under N 2 atmosphere to generate the phosphine‐containing products in up to 83% yield (Scheme 41b).…”