Catalytic asymmetric cyclopropanation of alkenes with diazoesters in protic and biphasic media

Bisoxazoline ligands with an axial-unfixed biaryl backbone: the effects of the biaryl backbone and the substituent at oxazoline ring on Cu-catalyzed asymmetric cyclopropanation

“…With copper(I) triflate, all of these ligands also afford only one kind of the C 2 -symmetric complex besides ligands 5a, 6a, and 7a having hydroxyl groups, which gave broad signals in 1 H NMR spectra on complexation, perhaps due to the low solubility of the complexes in the solution. 11 From the little difference in the chemical shifts of the alkoxyl groups of the complex and those of the ligand in 1 H NMR spectra, it can be concluded that the oxygen atom in the substituent at oxazoline ring does not coordinate with the copper(I) ion. Therefore, the complexes formed should be C 2 -symmetrically N,N 0 -coordinated, the structure of which could be deduced to be (aR)-19.…”

N-Propylphthalimide-Substituted Silver(I) N-Heterocyclic Carbene Complexes and Ruthenium(II) N-Heterocyclic Carbene Complexes: Synthesis and Transfer Hydrogenation of Ketones

“…Recently, the newly synthesized Ru complexes have provided with particularly ligands to maintain a compatible equilibrium between the electronic and steric environment around the metal and to control on their stability, activity and chemoselectivity profiles [19][20][21][22][23][24][25][26][27][28][29][30]. Typically, most of NHC ligands emerge quite suitability with heteroatom including air, moisture and functional groups, thus expanding areas of application [31] in the many organic transformations.…”

Ruthenium‐Catalyzed Cyclopropanation

“…The introduction of a hydroxymethyl group on the oxazoline ring of Pybox (Pybox-hm) can provide a water-soluble catalyst of ruthenium 5 (Table 7.1) [6]. Compared to a toluene solution, toluene-water in a double-phase system improves the yield and also the trans:cis ratio.…”