Intramolecular biaryl coupling

In most cases, construction of axial nonracemic biaryls can be realized by metal-mediated intramolecular biaryl coupling in which the chirality is induced by ort/io-substituted auxiliaries in an aromatic system. 

An extension of the intramolecular biaryl coupling with PIFA-BF3 Et20 to a short and efficient access to benzo[c]phenanthridines (60) and phenanthri-... 

Phenolic or non-phenolic oxidative coupling methods have been extensively used since the 1970 s to synthesize polyoxygenated bridged biaryl compounds, as will be illustrated later in the case of steganes. Remarkably enough, the use of transition metal oxidants is particularly suited to perform intramolecular biaryl coupling whereas most other methods are better suited to intermodular coupling. 

Pd-catalyzed Stille-Kelly coupling Pd-catalyzed intramolecular biaryl coupling of aryl halides or aryl triflates in the presence of distannanes. 440... 

Kelly, T. R., Li, Q., Bhushan, V. Intramolecular biaryl coupling asymmetric synthesis of the chiral B-ring diol unit of pradimicinone. 

The classical Ullmann reaction has also attracted renewed interest in recent years. Miyano has prepared optically enriched binaphthyl derivatives by intramolecular biaryl coupling, as shown in equation (9). " Diastereoselectivities of up to 70% have been obtained with a binaphthol chiral auxiliary in the linking chain. Intermolecular cross-coupling is best accomplished with preformed arylcopper compounds. "... 

Lipshutz and coworkers synthesized an optically active BINOL analog by copper-catalyzed intramolecular biaryl coupling and applied the complex with Ti(0 Pr)4 7 to Keck s asymmetric allylation [23]. In the reaction with benzalde-hyde or cyclohexanecarboxaldehyde, almost identical results were obtained with regard to both yields of isolated product and enantiomeric excesses. 

Other oxidants like thallium(III) oxide, vanadium(V) oxyfluoride, palladium ) acetate, and ruthenium(IV) tetrakis(trifluoracetate) have been developed as powerful tools for the intramolecular biaryl coupling reaction [7,93,113]. Nevertheless, DDQ is still one of the most versatile reagents in oxidative coupling reactions (see Scheme 14 and 29 [82,114]). The highly strained dioxa[8](2,7)pyrenophane (65), portraying an overall curvature of nearly 90° for the pyrene subunit, was finally obtained from the mefa-cyclophanediene (66) by dehydrogenation with DDQ in refluxing benzene in 67% yield [114]. 

The authors then extended this methodology to prepare 1457, the requisite precursor for testing the critical intramolecular biaryl coupling. The expected... 

Scheme 6.44 An intramolecular biaryl coupling of a bis(bromophenyl)pyrazol involving...

In 2005, Fagnou achieved the formal synthesis of (—)-allocolchicine through a palladium-catalyzed intramolecular C-H/C-X coupling [411]. The intramolecular biaryl coupling of 1,3-diarylpropane precursor 40 proceeded in the presence of Pd(OAc)2> DavePhos (41), and K2CO3 at 145 °C to furnish the seven-membered ring in 42. Deprotection of the methoxy methyl ether (MOM) group by HCl, followed by... 

In 1990, while working on the total synthesis of pradimicin, Kelly discovered that the treatment of a biaryl halide (46) or triflate in presence of hexaalkyldistannane (47) and a catalytic amount of Pd(PPh3)4 led to the clean intramolecular biaryl coupling to produce 48 in 80% isolated yield. This reaction can be regarded as the transmetalation with the distannane mediated by palladium to afford the intermediate organostannane 49 which then... 

In their first attempts, they applied the original protocol published by Miyaura and associates using K2CO3 as the base on several haloarenes and were pleased to obtain the corresponding biaryls in good to excellent yields (Experimental Procedure below). Recently, MacMillan and co-workers used a similar protocol for the intramolecular biaryl coupling targeting the natural product diazonamide. ... 

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