Palladium Catalyzed Regioselective Cyclization of Arylcarboxylic Acids via Radical Intermediates with Diaryliodonium Salts

Abstract

Palladium-catalyzed C2-arylation/intramolecular acylation with arylcarboxylic acids was developed by using diaryliodonium salts. The protocol has the advantage of good step-economy by two chemical bonds formation in one pot.

Diaryliodonium(iii) salts in one-pot double functionalization of C–IIIIandorthoC–H bonds

“…Carboxylic acid also serves as a directing group for the C–H palladation step (Schemes 34 and 35). 69,70 Han and coworkers reported the reaction of diaryliodonium triflate and 1-naphthoic acid 93 producing benzanthrone derivatives 94 in the presence of a palladium catalyst and triflic acid (Scheme 34) 69 In this reaction, C–H bond palladation occurs at the C8 position rather than at the C2 position to generate a cyclic palladium( iv ) species 94-int-a . The second C–C bond formation proceeds through intramolecular electrophilic substitution of 94-int-b induced by triflic acid.…”

“…The use of NaO t Bu instead of triflic acid afforded fluorenone derivatives 95 (Scheme 35). 70 The authors proposed that an acyl radical ( 95-int-c ) is the reaction intermediate, which is generated via 95-int-b assisted by NaO t Bu and diaryliodonium triflate. Sequential carbonylative cyclization furnishes the final product 95 .…”

“…Carboxylic acid also serves as a directing group for the C-H palladation step (Schemes 34 and 35). 69,70 Han and coworkers The oxidative addition of aryl bromide also induces palladacycle formation even in the absence of directing groups (Scheme 36). The combination of diaryliodonium triflate and 2-bromobiphenyl 96 afforded triphenylene 97 in the presence of a Pd(PPh 3 ) 4 catalyst.…”

Recent Progress in Cyclic Aryliodonium Chemistry: Syntheses and Applications

“…Structurally, aryliodonium salts can be classified into two categories: acyclic and cyclic aryliodoniums. Because of their high reactivity, air/moisture stability, and ready availability, acyclic aryliodoniums have been extensively utilized as efficient arylation reagents in organic synthesis. ,− For example, cross-coupling reactions involving acyclic aryliodoniums with carbonyl moieties, alkynes, alkenes, , and hetero atoms to construct various functionalized molecules − are realized. Compared to acyclic aryliodoniums, cyclic counterparts are less explored, although they could be employed for further transformations to set up a cascade reaction to achieve reaction economy.…”

Fe-Catalyzed Difunctionalization of Aryl Titanates Enabled by Fe/Ti Synergism

“…The synthetic application of the present ODFs was further demonstrated in the preparations of compounds 5 and 6 (Scheme ). The tetracyclic motifs of the benzofluorenes are widely found in natural products and advanced organic materials. − By using the present ODF, aryl and COOEt groups were incorporated onto the naphthalene nucleus in a one-pot and regiocontrolled manner, and the subsequent cyclization furnished the benzofluorene 5 , an intermediate for electroluminescent devices, in a 63% overall yield. Compound 6 is an important intermediate for the syntheses of juncusol and etiojervane .…”