Efficient Synthesis of Phenanthridinone Derivatives via a Palladium-Catalyzed Coupling Process†

Highly selective palladium-catalyzed Suzuki–Miyaura monocoupling reactions of ethene and arene derivatives bearing two or more electrophilic sites

Synthesis of hydroxylated oligoarene-type phosphines by a repetitive two-step method

A versatile and efficient approach for the synthesis of new biphenyl-based arsine ligands, by a Pd-catalyzed arsination to introduce the -AsPh2 moiety, and then a Suzuki–Miyaura cross-coupling for biaryl construction is reported. By Pd-catalyzed arsination with n-Bu3SnAsPh2 (1), (2-bromophenyl)diphenylarsine (2, 83%) was obtained. The Suzuki–Miyaura reaction between the bromoarsine 2 and aryl boronic acids bearing different substituents provided biarylarsine ligands (80–99%). The efficiency of catalysts derived from the new biarylarsine ligands was evaluated in the Pd-catalyzed arsination with perfluoroalkyl iodides (RfI). Outstanding activities of catalysts derived from Pd/methoxybiarylarsine ligands were found in this coupling reaction affording perfluoroalkyl arsines in very good yields (57–100%).

Synthesis of biphenyl-based arsine ligands by Suzuki–Miyaura coupling and their application to Pd-catalyzed arsination

Two alternative routes are described for the synthesis of 8-aryl-2-tetralones (1). Route A starts from alpha-tetralone 3 and involves 3 or 4 steps, with the selective Na-EtOH reduction of 1-aryl-7-methoxynaphthalenes 2 being the key step. The exclusive reduction of the A ring of naphthalenes 2 occurs when the aryl group at C-1 has no substituent at the ortho positions, affording tetrahydronaphthalenes 11. Reduction of the B ring of 2 becomes the major process when the aryl fragment has two substituents at the ortho positions, affording 8-aryl-2-tetralones 1 as the major component. Route B involves 5 steps starting from 2-tetralone 5, with the key step being the Suzuki coupling with triflate 4. This approach allows the synthesis of 8-aryl-2-tetralones 1 with no substituent at the ortho positions of the aryl fragment and with naphthalene and anthracene rings at C-8.

General synthesis of 8-aryl-2-tetralones.

Synthesis of novel 1-aryl-substituted 8-methoxynaphthalenes and their tendency for atropisomerization

Novel phenylnaphthyl phosphines were prepared and applied to the Pd-catalyzed intramolecular amidation. Both ligands gave good to excellent yields in the synthesis of five-, six-, and seven-membered rings from halo-amidesand carbamates.

Synthesis of Novel Phenylnaphthyl Phosphines and their Applications to Pd-Catalyzed Intramolecular Amidation

Novel 1-aryl-substituted 8-methoxynaphthalenes were conveniently prepared by using Suzuki–Miyaura cross-coupling as a key reaction. Chemical transformations of the coupled products gave a variety of biaryls bearing various functional groups. The optical behavior of the separated enantiomers of these derivatives was also investigated by HPLC analysis. The optical resolution and determination of absolute configuration of novel binaphtyl derivative were also described. These new compounds may have some potential as mono- or bidentate ligands for metal-catalyzed chemical transformations including asymmetric induction.

Jun-ichi Odaira

Papers

Synthesis of novel 1-aryl-substituted 8-methoxynaphthalenes and their tendency for atropisomerization

Synthesis of Novel Phenylnaphthyl Phosphines and their Applications to Pd-Catalyzed Intramolecular Amidation

Synthesis of Novel 1-Aryl-Substituted 8-Methoxynaphthalenes and Their Tendency for Atropisomerization.