Synthesis of Fluoren-9-ones and Ladder-Type Oligo-p-phenylene Cores via Pd-Catalyzed Carbonylative Multiple C–C Bond Formation

Abstract

A new route to various substituted fluoren-9-ones has been developed via an efficient Pd-catalyzed carbonylative multiple C-C bond formation. Under a CO atmosphere, using commercially available aryl halides and arylboronic acids as substrates, this three-component reaction proceeded smoothly in moderate to excellent yields with good functional-group compatibility. The mechanistic investigations suggested a sequential process for the reaction that forms o-bromobiaryls in the first stage followed by a cyclocarbonylation reaction. This chemistry has been successfully extended to construct ladder-type oligo-p-phenylene cores.

Expeditious Assembly of Fluorenones through Domino Reactions of Benzoyl Chlorides with Arylboronic Acids Catalyzed by ONO Pincer‐like Palladium(II) Complexes

“…Most prominently, Xie et al . reported the synthesis of fluorenones through Pd‐catalyzed multiple C−C bond formation under a CO atmosphere.…”

A Perspective on Synthesis and Applications of Fluorenones

“…It was speculated that aryne generated from silyl triflate coordinates with Pd 0 and propagates the palladium cycle. Oxidative addition takes place of 2-iodobenzaldehyde (39) to palladium(II) complex (42) resulting in palladium(IV) complex (43). Due to the reductive elimination of (43) to generate intermediate (44), which may further undergo carbonylation and subsequently undergoes β-elimination (acylation pathway) or CÀ H bond activation via organopalladium intermediate (46).…”

Synthesis of Heteroarene‐Fused Cyclopentadienes and Related Compounds Suitable for Metallocene Preparation

“…[153] Transformation of the acid into the acyl chloride with subsequent cyclization produced 4H-indeno[1,2-b]thiophen-4-one 200. A catalytic route to this compound via carbonylation and reaction with 2-thienylboronic acid was proposed by Song et al, [154] and Pd-catalyzed cyclizations of chloro-substituted benzoylthiophenes [84,85] were also studied (Scheme 31). The target compound 201 was obtained in high yields by the Wolff-Kishner reduction of ketone 200.…”

“…Synthesis of 4H-indeno[1,2-b]thiophene 201. [84,85,[149][150][151][152][154][155][156] Scheme 32. Preparation of substituted 4H-indeno[1,2-b] thiophene derivatives.…”