title: Developing five-membered heterocycle substituted phosphinous acids as ligands for palladium-catalyzed Suzuki-Miyaura and Catellani reactions.
abstract: A new category of secondary phosphine oxides (SPOs) (5a-5j) with/without benzo-fused five-membered heterocyclic substituents were prepared. These new compounds are air- and moisture-stable ligands and have the advantage of long-term storage. Some of the ligands as well as ligand coordinated palladium complexes (6f' and 6f'') and platinum complexes (7b_trans & 7i_trans) were prepared and their structures were determined using single crystal X-ray diffraction methods. The crystal structure of 6f' revealed the formation of diamond shape di-palladium complexes with a Pd2Cl2 core. As for the structures of 7b_trans & 7i_trans, the processes for the generation of the trans-form of the bis-phosphine ligand coordinated platinum complexes are shown. These SPOs exhibit notable efficiencies in palladium-catalyzed Suzuki-Miyaura reactions. Moreover, organic compounds (9k and 10c) with unexpected conformations were obtained from Heck-type Catellani reactions. Reaction pathways are proposed to accommodate the probable routes for the formation of all organic products.
authors.affiliation: Department of Chemistry, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan. fehong@dragon.nchu.edu.tw.
authors.forename: Ting-Wei
authors.initials: TW
authors.lastname: Chang
authors.forename: Pei-Yun
authors.initials: PY
authors.lastname: Ho
authors.forename: Kuo-Chung
authors.initials: KC
authors.lastname: Mao
authors.forename: Fung-E
authors.initials: FE
authors.lastname: Hong