Letter pubs.acs.org/OrgLett
Cite This: Org. Lett. XXXX, XXX, XXX−XXX
Synthesis of peri-Substituted (Naphthalen-1-yl)phosphine Ligands by Rhodium(I)-Catalyzed Phosphine-Directed C−H Arylation Xue Luo,†,§ Jia Yuan,†,§ Chang-Duo Yue,† Zi-Yang Zhang,† Jian Chen,† Guang-Ao Yu,*,† and Chi-Ming Che*,‡ †
Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, and Chemical Biology Center, College of Chemistry, Central China Normal University, Wuhan 430079, People’s Republic of China ‡ State Key Laboratory of Synthetic Chemistry, and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China S Supporting Information *
ABSTRACT: A novel protocol for effective rhodium(I)catalyzed C−H arylation of tertiary phosphines has been devised. It is amenable to a wide range of substrates and gives the products in moderate to high yields. This strategy provides a simple and efficient route to peri-substituted (naphthalen-1yl)phosphines.
Table 1. Screening of the Reaction Conditionsa
peri-Substituted naphthalenes display unique geometry. The natural geometry of naphthalene is planar, with all angles close to 120°, which results in the “ideal” peri distance of ca. 2.5 Å. The peri-distance is the intermediate between ortho- and bayregion distances (Figure 1). This unique geometry makes them potentially applicable in electroluminescent materials and organic transformations.1 Tertiary phosphines remain the most widely used ligands in organometallic chemistry and catalysis, because their electronic and steric properties are more easily modified than those of other ligands.2 Among them, naphthalene-1,8-diyl phosphines have received increasing attention in recent decades, owing to their utility as rigid bidentate C3 symmetric ligands in organometallic complexes (Figure 1). However, modification of the backbones of such
entry
catalyst (mol %)
base
temp (°C)
conv (%)b
1 2 3 4 5 6 7 8 9 10 11 12
[Rh(cod)Cl]2 (2.5) [Rh(cod)Cl]2 (2.5) [Rh(cod)Cl]2 (2.5) [Cp*RhCl2]2 (2.5) Ru(cod)Cl2 (5) Pd(OAc)2 (5) [Ir(cod)Cl]2 (2.5) [Rh(cod)Cl]2 (1.0) [Rh(cod)Cl]2 (2.5) [Rh(cod)Cl]2 (2.5) none [Rh(cod)Cl]2 (2.5)
tBuOLi tBuONa tBuOK tBuOLi tBuOLi tBuOLi tBuOLi tBuOLi tBuOLi tBuOLi tBuOLi none
140 140 140 140 140 140 140 140 110 70 140 140
95 77 85 67 12 21
