Cyclohepta[b]pyran: an important scaffold in biologically active natural products

Heterocycle-fused cycloheptanoid derivatives are one of the specific natural product scaffolds with a broad range of biological and pharmaceutical activities. Seven-membered carbocycles fused to the b-bond of a pyran ring are termed cyclohepta[b]pyrans. Most of the naturally occurring compounds containing cyclohepta[b]pyran scaffold display various biological activities such as antiplasmodial, antimicrobial, antitumor, antileishmanial, anti-inflammatory, enzyme inhibition, and other effects. Therefore, this substructure is important enough to be reviewed. This review summarizes that 92 compounds containing cyclohepta[b]pyran subunit have been isolated and characterized in the past few decades. Different organisms from plants to fungi produce these secondary metabolites. Furthermore, the biological activity of the given metabolites is presented, where known. The literature findings presented in this review can be used as the basis for further research on cyclohepta[b]pyran substructure.