The Synthesis And Characterize Of Novel Diphosphite Ligands And Their Application In Buchwald–Hartwig Reaction

Phosphine ligands and phosphite ligands were widely used in the organic reaction, these ligands complexes of such metals can be used as catalysts for asymmetric catalytic reactions. The phosphite ligands are regulatability feature of the structure by compared with the phosphine ligands. Phosphite ligands can be divided into monophosphite ligands and diphosphite ligands. The diphosphite ligands are conveniented to synthesis, stability in the air, regulatability feature of the structure and chelating closed with metal by compared with the monophosphite ligands and they are able to catalyze the reaction very well.In this paper, we designed five novel diphosphite ligands and synthesized in which three ligands successfully. In addition, we synthesized other ligands such as L1 and L3 derived from ethylene glycol and 1,3-propylenediol which had been reported. By our designed new ligands and ligands have been reported compared and studied their differences in the catalytic properties of the reaction among that it could provide some data and experience accumulated for the future ligands design. Wherein L5, L6, L7 were new compounds and characterized by 31 P NMR, 1H NMR, 13 C NMR, HRMS and IR. We preliminary studied of the application of diphosphite ligands in the Buchwald-Hartwig reaction. The main works were shown as follows: 1. The synthesis and characterization of novel diphosphite ligands.The novel diphosphite ligands were prepared from 3,3’,5,5’-tert-butyl-2,2’-dihyroxy diphenyl, phosphorus thichloride, triethylamine and diol by two-step reaction “one-pot” method(Scheme 1) and their structure were characterized.2. The application of new diphosphite ligands in the Buchwald-Hartwig reaction. We preliminary studied of the application of diphosphite ligands in the Buchwald-Hartwig reaction with good yield. Our reaction of bromobenzene with morpholine as a template, the effects Buchwald-Hartwig amination was evaluated with different palladium source, solvents, base, various ligands, reaction time and the amount of catalyst at different reaction temperatures. We have achieved the optimum reaction conditions which was 2.5% mol Pd2(dba)3 as the catalyst, 5% mol L6 as the ligand and Na OtBu as the base in toluene at 100 ℃ for 1 h under N2 atmosphere. Under optimal conditions, aryl halides, heteroaryl chlorides and various amines were expanded, it showed that the reaction had better substrate universality and achieved good to excellent yield(Scheme 2).