Research On Chiral Pcp-pincer Palladium Complexes And N-heterocyclic Carbene(nhc)-copper Complexes-catalyzed Hydrophosphination Of Michael Acceptors

This thesis focused on the enantioselective conjugate addition reactions of chiral metal-phosphido species with Michael acceptors. This research directedly led to disclose three new reactions, including N-heterocyclic carbene-copper complex catalyzed hydrophosphination ofα,β-unsaturated carbonyl compounds and chiral PCP-pincer Palladium complexes catalyzed hydrophosphination ofα,β-unsaturated ketones and nitroalkenes. These new reactions provide efficient and atom economical methods for the synthesis of chiral phosphanes.1. N-heterocyclic carbene-copper complexes catalyzed hydrophosphination ofα,β-unsaturated carbonyl compoundsThe SIPrCuCl-catalyzed conjugate addition reactions of diarylphosphine withα,β-unsaturated carbonyl compounds have been realized to provided an effective synthetic protocol for the preparation of theβ-carbonylphosphines under mild conditions without addition of base. After screening various chiral NHC-Ligands, we have developed the first NHC-Copper-catalyzed asymmetric hydrophosphination ofα,β-unsaturated ketone.2. Chiral PCP-pincer Palladium complexes catalyzed hydrophsophination ofα,β-unsaturated ketonesWe have developed the first Palladium-catalyzed enantioselective 1,4-addition of trivalent phosphine to enones. Catalyst (S,S)-3-7 has been found to catalyze the phospha-Michael reaction of diaryphosphines toα,β-unsaturated ketone with high yield and high enantioselectivities (up to 93% yield, up to 99% ee). On the basis of the preliminary 31P NMR experiments for the observation of PCP-Pd-PPh2 intermediate and the preparation of the pincer Palladium phosphonium tetrafluoroborate 3-9, we proposed a reasonable mechanism which involved deprotonation of diaryphosphines by (S,S)-3-7 to form the PCP-Pd-PAr2 intermediate. Furthermore, we had applied this methodology to the synthesis of the C2-symmetric diphosphanes DPPP and chiral PCP-pincer Palladium complexes 3-11.3. Chiral PCP-pincer Palladium complexes catalyzed hydrophosphination of nitroalkenesIn this part we succeeded in applying catalyst (S,S)-3-7 to hydrophosphination of nitroalkenes. Under the optimal condition, catalyst (S,S)-3-7 has been found to catalyze the enantioselective conjugate addition reactions of diaryphosphines withβ-aryl orβ-alkyl substituted nitroalkenes with 62-92% yield and 61-91% ee at-10℃.