Wide bite angle amine, arsine and phosphine ligands in rhodium- and platinum/tin-catalysed hydroformylation †

Sterically Demanding Diphosphonite Ligands –Synthesis and Application in Nickel‐Catalyzed Isomerization of 2‐Methyl‐3‐Butenenitrile

“…We explored the isomerization capabilities of several Ni complexes with some xanthene derived diphosphine ligands [POP-Xantphos, DBP-Xantphos [29] and 2,7-(ditert-butyl)Xantphos] as well, for which the results are listed in Table 5. As was observed in preliminary 31 P NMR studies, these ligands readily form bischelates.…”

“…[28] POP-Xantphos is a derivative which includes a rigid phenoxaphosphine cycle ( Figure 4). [29] Based on molecular modelling calculations, the natural bite angle is 123.18 with a flexibility range of 107 ± 1428 and the ligand has been shown to be active in the hydroformylation of 1-octene and trans-2-and -4-octene. The complexation behaviour of these ligands with nickelprecursors was investigated by 31 P NMR spectroscopy.…”

Synthesis of Dibenzofurans Directly from Aryl Halides and ortho-Bromophenols via One-Pot Consecutive SNAr and Intramolecular Palladium-Catalyzed Aryl-Aryl Coupling Reactions

“…

Tandem reactions involve a sequence of reactions performed in the same reaction vessel.1) Nowadays, tandem reactions have emerged as powerful tools to meet the demands of modern organic chemistry due to the synthetic efficiency, molecular diversity, and low production costs, etc.2-5) Recently, we discovered tandem sequences for the efficient synthesis of diaryl ethers from arylmethanesulfonates and aryl halides.6) Meanwhile, it is well-known that dibenzofurans are good candidates for the study of molecular recognition, [7][8][9] catalytic reactions [10][11][12] and the geometry of metal-binding sites.13) Although Ames et al had reported the synthesis of dibenzofurans, step-wise procedures were needed and the corresponding yields were also not good 14) ; lately, Liu et al discovered that the dibenzofurans could be prepared by the reaction of ortho-iodophenols with silylaryl triflates in the presence of CsF and palladium, but expensive and excess base and not easily available starting material were used.

15)Thereby, the construction of dibenzofurans with simple, cheap and easily available organic molecules and base in a facile and efficient one-pot reaction is highly desirable. In the continuation of our program aimed at the discovery and development of new tandem reactions, 6) herein we report the synthesis of dibenzofurans directly from aryl halides with ortho-bromophenols via one-pot C(sp 2 )-O bond formation reaction (SNAr) in the presence of anhydrous K 2 CO 3 , followed by C(sp 2 )-C(sp 2 ) bond formation reaction (intramolecular aryl-aryl coupling reaction) catalyzed by Pd(OAc) 2 (Chart 1).

Results and Discussion

Dibenzofurans were efficiently and conveniently prepared via one-pot C(sp 2 )-O bond formation reaction (SNAr), followed by C(sp 2 )-C(sp 2 ) bond formation reaction (intramolecular palladium-catalyzed aryl-aryl coupling reaction) between aryl halides and ortho-bromophenols.

…”

“…[2][3][4][5] Recently, we discovered tandem sequences for the efficient synthesis of diaryl ethers from arylmethanesulfonates and aryl halides. 6) Meanwhile, it is well-known that dibenzofurans are good candidates for the study of molecular recognition, [7][8][9] catalytic reactions [10][11][12] and the geometry of metal-binding sites. 13) Although Ames et al had reported the synthesis of dibenzofurans, step-wise procedures were needed and the corresponding yields were also not good 14) ; lately, Liu et al discovered that the dibenzofurans could be prepared by the reaction of ortho-iodophenols with silylaryl triflates in the presence of CsF and palladium, but expensive and excess base and not easily available starting material were used.…”

“…6) Meanwhile, it is well-known that dibenzofurans are good candidates for the study of molecular recognition, [7][8][9] catalytic reactions [10][11][12] and the geometry of metal-binding sites.…”