First isolation of disubstituted cis‐5,6‐dihydro‐1,10‐phenanthrolines. lipase‐mediated resolution of cis‐ and trans‐phenoxy alcohol isomers and assignment of absolute stereochemistry via cd and nmr spectroscopy

Abstract

5,6-Dihydro-1,10-phenanthrolines can display axial and central chirality. In conjunction with the ligating properties of the diimino moiety, this class of compounds is of great interest to applications in supramolecular chemistry. We report the first preparation of cis-5,6-dihydro-1,10-phenanthroline derivatives by reacting triphenyl borate with the corresponding epoxide precursor. We found that solvent and temperature choice determined the stereoselectivity of the epoxide opening giving rise to the cis (14:1 dr) or trans (99:1 dr) product. Racemates of each stereoisomeric mixture, cis- and trans-phenoxy alcohol, were separated via highly enantioselective transesterifications with lipase PSCI from Burkholderia cepacia (97% ee, E > 200). Stereochemical assignments were carried out using CD and X-ray analyses in conjunction with NMR studies of α-methoxy-α-(trifluoromethyl)phenylacetic acid and α-methoxyphenylacetic acid esters.

Synthesis, structure, ultrafast kinetics, and light-induced dynamics of CuHETPHEN chromophores

“…[26][27][28] Phenanthroline ligands containing an epoxide in the 5,6-position are less common but have still been used to covalently link diverse functional groups. 40,41 Previously, it was shown that 1,10-phenanthroline-5,6-dihydro-5,6-epoxide can be opened using a variety of nucleophiles including alcohols, 42,43 amines, 44 and thiols 45 under mild conditions making it a good candidate to link a somewhat delicate Cu(I) compound to molecular catalysts, surfaces, or biomolecules. Therefore, we targeted the synthesis of a CuHETPHEN complex which features 2,9-dimethyl-5,6-dihydro-1,10-phenanthrolin-5,6-epoxide (L5, Scheme 1).…”