Regio- and Enantioselective Decarboxylative Allylic Benzylation Enabled by Dual Palladium/Photoredox Catalysis

Abstract

A decarboxylative allylic benzylation cocatalyzed by Pd/ photoredox in a regio-and enantioselective manner has been achieved. Readily available aryl acetic acids are used as benzylic nucleophile equivalents without preactivation. This mild and atom-economical protocol expands the scope of coupling partners of allylic electrophiles. Vinyl epoxides could also go through this transformation smoothly, affording various chiral homoallylic alcohols bearing all-carbon quaternary stereocenters.

Cu-Catalyzed decarboxylative annulation of N-substituted glycines with 3-formylchromones: synthesis of functionalized chromeno[2,3-b]pyrrol-4(1H)-ones

“…In synthetic organic chemistry, one of the most impactful events in recent years is the introduction of transition-metal catalyzed cross-coupling reactions. Among them, the decarboxylative cross-coupling of carboxylic acids is perhaps one of the most efficient methods of forming C–C, 1,2 C–N, 3 C–O, 4 C–S, 5 C–X, 6 and C–B bonds 7 among others 8 because of their well-known reliability, selectivity, and predictability. 1–5 As a result, more and more strategies have been developed to form the target compounds.…”

“…Among them, the decarboxylative cross-coupling of carboxylic acids is perhaps one of the most efficient methods of forming C–C, 1,2 C–N, 3 C–O, 4 C–S, 5 C–X, 6 and C–B bonds 7 among others 8 because of their well-known reliability, selectivity, and predictability. 1–5 As a result, more and more strategies have been developed to form the target compounds. 1–8 Only some examples of the reactions from the decarboxylative cross-coupling of carboxylic acids have been used to construct some kinds of natural-like heterocyclic compounds via the annulation reaction with amines (forming the C–N bonds) 9 and enolizable substrates (forming the C–C bonds).…”

“…1–5 As a result, more and more strategies have been developed to form the target compounds. 1–8 Only some examples of the reactions from the decarboxylative cross-coupling of carboxylic acids have been used to construct some kinds of natural-like heterocyclic compounds via the annulation reaction with amines (forming the C–N bonds) 9 and enolizable substrates (forming the C–C bonds). 10 There have been rare studies reported on the annulation of carboxylic acids with the acyl group of aldehydes ( i.e.…”

Asymmetric Formal Nucleophilic o-Cresolylation with Morita–Baylis–Hillman Carbonates of 2-Cyclohexenones via Palladium Catalysis

“…Hence the benzylation process, especially in a catalytic manner, has been widely investigated by chemists. Some new protocols, such as direct benzylic C­(sp 3 )–H activation and cross-coupling reaction of benzylic halides under transition metal or photocatalysis, have illustrated the capability to produce the benzylated substances, but some challenges remain to be resolved for enantioselective reactions. Traditional electrophilic benzylation processes, usually involving the S N 1 or S N 2 mechanism mediated substitution reaction of benzyl (pseudo)­halides and dearomative benzylic π-allylmetal complexes, or even pre-prepared and in situ generated quinone methides with a driven force to aromatization via 1,4-addition or [4 + n ] annulations, contributed tremendously.…”

Synthesis of Pleuromutilin

“… , Ultimately, application of iridium complex 17 as a catalyst secured access to product 26 in good yield under optimized conditions (entry 2), where inclusion of TEMPO was critical to achieving high efficiency (cf. entry 3). − This transformation likely involves trapping of the intermediate cyclobutyl radical with oxygen or TEMPO and a Criegee- or Grob-type fragmentation to eventually generate the diketone motif . Silver­(I)-based reagents proved incompetent in the desired oxidation (e.g., entry 4) and instead appeared to preferentially engage the cyclobutanol motif in a cleavage of the C11–C12 bond .…”