Synthesis of fused multicyclic compounds containing macrocycles by dienyne ring-closing metathesis and Diels–Alder reactions

Abstract

Fused bicyclic compounds comprising small and large rings were synthesised by dienyne ring-closing metathesis (RCM) using Grubbs’ catalyst. By taking advantage of faster small ring cyclisation compared with macrocyclisation, single isomers were obtained rather than mixtures of two isomers with different ring sizes. Using this process, various fused bicyclic compounds comprising small rings (5–7- membered) and large rings (14–17- membered) were obtained. By increasing reaction temperature and catalyst loading, the product conversion was improved in a predicted manner. This method produced E-olefins on the macrocycles with high selectivity. Also, the selectivity issues of tandem RCM for the synthesis of fused bicyclic compounds comprising small and medium rings were investigated. Lastly, the prepared bicyclic compounds with small and large rings contained 1, 3-dienes that underwent a further modification reaction, such as Diels–Alder, to produce more complex compounds. These Diels–Alder reactions produced tri- and tetracyclic compounds containing a macrocycle with single diastereomers, suggesting that the methodology demonstrated here could be a powerful tool for rapid preparation of highly complex molecules.