Macrocyclic alkene containing bisimidazole showing molecular asymmetry, which is synthesized by ring-closing metathesis, is subjected to several functional group transformation reactions of the olefin moiety. Syn-addition reactions such as epoxidation, dihydroxylation, and hydrogenation are found to proceed whereas anti-addition does not proceed. Optical resolution of racemic bisimidazole is successfully achieved with a preparative chiral column. Racemization behaviors of bisimidazole derivatives are also studied under several conditions. Scheme 1. Formation of macrocyclic bisazole 2 by RCM.

The chirality of winding vine-shaped heterobiaryls with molecular asymmetry is recognized by a sugar-based chiral oxidant. Kinetic resolution of (±)-bisbenzoimidazole bearing an olefin moiety takes place with Shi’s asymmetric epoxidation to observe krel value up to ca. 35 affording the corresponding epoxide. The reaction of a (±)-bithiophene derivative also recognized the chirality to give the corresponding epoxide with er of 96:4 at 39% conversion. Dynamic kinetic resolution is found to take place when unsymmetrical biaryl composed of benzoimidazole/thiophene is subjected to Shi’s epoxidation, whose conversion of the racemic substrate exceeds to 50%.

Oxidative condensation of N-(3-buten-1-yl)-1,2-phenylenediamine with a formylated heteroarene bearing 3-buten-1-yl substituent gives unsymmetrical heterobiaryl in 42-86% yields. Ring-closing metathesis of the thus obtained product affords the cyclized product, which resulted in separation of each enantiomer by HPLC with a chiral column showing molecular asymmetry.