Preparation of Chiral 5,6‐trans‐Disubstituted Phenanthrolines from Phenanthroline‐5,6‐epoxide.

Abstract

Fused pyridine derivativesFused pyridine derivatives R 0450 Preparation of Chiral 5,6-trans-Disubstituted Phenanthrolines from Phenanthroline-5,6-epoxide. -The trans-selective ring opening of the epoxide (I) with primary amines and sodium azide is investigated in the presence of basic alumina or magnesium perchlorate as the Lewis acid. -(SCHOFFERS*, E.; TRAN, S. D.; MACE, K.; Heterocycles 60 (2003) 4, 769-772; Dep. Chem., West. Mich. Univ., Kalamazoo, MI 49008, USA; Eng.) -Mais 31-160

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

“…We previously found that magnesium perchlorate and alumina catalyzed the ring‐opening of epoxide 1 with nitrogen nucleophiles, whereas oxygen nucleophiles required a stronger Lewis acid, ytterbium(III) triflate 48, 51. Reactions proceeded with a variety of alcohols in 81–99% yield but attempts to use phenol were unsuccessful.…”

“…B‐ring‐modified 5,6‐dihydro‐1,10‐phenanthrolines have unique structural properties and can display axial chirality and/or central chirality; the latter typically referring to the presence of one or more stereogenic centers in the absence of an axis or plane 45–47. A few derivatives were recently prepared via epoxide‐opening with oxygen‐ and nitrogen nucleophiles,48–51 and via intramolecular Ullmann coupling of two ethyl‐bridged pyridine rings 52. Until now no optically active cis ‐5,6‐dihydro derivatives that contain axial and central chirality have been reported.…”