3594-91-0Relevant articles and documents
New biphenyl iminium salt catalysts for highly enantioselective asymmetric epoxidation: Role of additional substitution and dihedral angle
Bulman Page, Philip C.,Bartlett, Christopher J.,Chan, Yohan,Allin, Steven M.,McKenzie, Michael J.,Lacour, Jér?me,Jones, Garth A.
, p. 4220 - 4232 (2016/05/24)
New biaryl iminium salt catalysts for enantioselective alkene epoxidation containing additional substitution in the heterocyclic ring are reported. The effects upon conformation and enantioselectivity of this additional substitution, and the influence of dihedral angle in these systems, has been investigated using a synthetic approach supported by density functional theory. Enantioselectivities of up to 97% ee were observed.
New, axially chiral, bimetallic catalysts for asymmetric alkylation of aldehydes with diethylzinc
Keller, Felix,Rippert, Andreas Johannes
, p. 125 - 137 (2007/10/03)
Axially chiral bis(salicylidene)ethylenediamine (H2salen)-type ligands 3 (cf. Schemes 1 and 3) are efficient ligands for the enantioselective addition of diethylzinc to aldehydes. There is ample evidence that an active bimetallic catalyst forms an effective chiral pocket (see Fig. 2); of a series of first-row transition-metal complexes with these ligands, the most stereoselective were the Co(II) complexes (see Fig. 1). Best ee values as well as the fastest rates (see Tables 2 and 3) were obtained with these Co(II) complexes when an EtO substituent was present at C(3) of the salicylaldehyde residues of ligand 3 (R1 = EtO), i.e., complex [Co(II)(3'h)] produce d up to 93% ee with aromatic aldehydes and 78% ee for aliphatic aldehydes (see Table 4).