Synthesis And Application Of Palladium (â…¡) And Gold (â… ) Complexes Of N-Heterocyclic Carbene Ligands Based On 1,1'-Binaphthyl Scaffold

This thesis was mainly focused on the synthesis of N-heterocyclic carbene (NHC) ligands derived from 1,1'-binaphthalenyl-2,2'-diamine (BINAM) and their palladium(Ⅱ) and gold(Ⅰ) complexes, and applications of these complexes in the catalytic transformations.1 Synthesis and application of bidentate bis(NHC)-Pd(Ⅱ) complexesA series of axially chiral bis(NHC)-Pd(II) complexes I-la,b, I-2a-d, I-3a and I-4a-h bearing different coordinating counterions and N-substituents have been prepared from 1,1'-binaphthalenyl-2,2'-diamine (BINAM) and fully characterized by NMR, MS and IR spectroscopies et al.. The structure of complex I-4c was also confirmed by its single-crystal X-ray diffraction study.These bis(NHC)-Pd(II) complexes as catalysts were effective in Et2Zn-mediated enantioselective umpolung allylation of aldehydes with cyclohexenyl acetate. While the variation of coordinating anion counterions may significantly change the raction rate, the enantioselectivity was both affected by coordinating counterions on palladium center and N-substituents around the N-heterocycle. For both aromatic and aliphatic aldehydes, complex I-4b bearing bromide counterions and N-CH2Ph substituents was the best catalyst to afford the homoallylic alcohol products in moderate to excellent yields (58%-96%), modest enantioselcetivities (54%-66% ee), and good to excellent syn diastereoselectivities (up to> 99:1 dr).2 Synthesis and characterization of palladium(Ⅱ) complexes of chelating NHC-N donor hybrid ligandsA new class of palladium(Ⅱ) complexes of chelating NHC-N donor hybrid ligands such as NHC-sulfonamide (Ⅱ-7), NHC-phenoxyimine (Ⅱ-14), NHC-phenylimine (Ⅱ-18) and NHC-amine (Ⅱ-19) have been successfully synthesized in modest yields from optically pure 1,1'-binaphthyl-2,2'-diamine (BINAM).These complexes have been characterized by all NMR, MS and IR spectroscopic data. The structures of II-7,11-14 and 11-18 were also confirmed by single-crystal X-ray diffraction studies to exhibit tridentate chelating motifs around the palladium center, but complexⅡ-19 was proposed to comprise a bidentate chelating NHC-amine hybrid ligand and two bromide counterions.3 Bidentate bis(NHC)-palladium(II) complex-catalyzed dioxygenation of alkenesBis(NHC)-palladium(II) complex were successfully used to catalyze the dioxygenation of alkenes under mild conditions tolerant of air and moisture, by using PhI(OAc)2 as the oxidant for its PdⅡ/PdⅣcatalytic cycle. Cationic NHC-Pd2+ diaquo complexⅠ-2d exhibited the highest catalytic activity to give 1,2-dioxygenation products with good syn-diastereoselectivity for 1,2-disubstituted alkenes, but styrene derivatives often afforded both 1,2- and 1,1-dioxygenation products with electron-rich derivatives being more liable to form the 1,1-dioxygenation product.By isotopic labeling experiments, we also investigated the possible mechanism involving PdⅡ/PdⅣcatalytic cycle to reasonably reveal the distribution of different products and their diastereoselectivities.4 Synthesis and applications of monodentate NHC-Au(I) complexesA series of axially chiral NHC-Au(I) complexesⅣ-1,Ⅳ-2a,b and IV-3-11 have been successfully synthesized from 1,1'-binaphthalenyl-2,2'-diamine (BINAM) and fully characterized by NMR, MS and IR spectroscopies et al. The structures of complexesⅣ-1,Ⅳ-2a andⅣ-6 were also confirmed by single-crystal X-ray diffraction studies, exhibiting a nearly linear coordination geometry of NHC and anion counterion ligands around gold center.These NHC-Au(I) complexes could effectively catalyze the intramolecular hydroalkoxylation of allenes to afford the ether product. in excellent yields but with unsatisfactory low enantioselectivities (up to 24% ee).These NHC-Au(I) complexes as catalysts were successfully applied in the intramolecular cyclization of 1,6-enynes. ComplexⅣ-6 was examined to be the best catalyst giving the acetoxyl productⅣ-50a in up to>99% yield and 59% ee under 0℃condition.The oxidative rearrangement of 1,6-enynes could also proceed smoothly with these NHC-Au(Ⅰ) complexes as catalysts by using Ph2SO as the oxidant, which is in fact the interception of cyclopropane gold(I)-carbenoid intermediate B for the gold(I)-catalyzed rearrangement of 1,6-enyne. ComplexⅣ-2a afforded the best results of up to>99% yield and 65% ee for the corresponding aldehyde productⅣ-53 under the condition of 10℃.