Chapter 3 - Macrocyclic Bisbibenzyls: Properties and Synthesis

Abstract

Abstract Macrocyclic bisbibenzyls (MBBs) are a class of naturally occurring compounds found mainly in liverworts species. Until now, over 70 biologically active MBBs have been isolated. With few exceptions, the core structure of MBBs comprises four aromatic rings. Most of the MBBs fall into two categories: (1) C,D-ring is linked through a biarylether bond and (2) C,D-ring is linked through a biaryl bond. In the past 30 years, isolation and structural elucidation have revealed a plethora of MBBs which bear interesting structures and properties. Among them, riccardins and marchantins are found to exhibit pleiotropic pharmacological activities, including antifungal activity, liver X receptor-modulating activity, anticancer activity, and NOS-inhibiting activity. Other MBBs members like cavicularin and isoplagiochin C have also drawn considerable attention from synthetic community due to their fascinating and unique molecular architecture. Although they have no stereocenters, they were found to be optically active. These phenomena suggested that these molecules possess conformational chirality. In this review, we will discuss the isolation and interesting properties (both biologically and structurally) of some typical MBBs. This review will also (and mainly) cover the recent synthetic approaches toward MBBs.