Studies on ring-closing metathesis for the construction of fused bicyclic ring systems

Abstract

Fused bicyclic rings [n,m,0] are common structural elements present in many natural products. Despite remarkable progress, methods and strategies that can simplify their construction are still in much demand. Ring-closing metathesis (RCM) is widely used for the synthesis of complex cyclic compounds, including natural products. RCM by using the Grubbs’ catalyst is recognized as one of the most powerful and useful methodologies in synthetic organic chemistry. We were interested in the conversion of acyclic dienynes to fused bicyclic [n,m,0] rings containing five, six, seven and eight-membered rings by using a Grubbs’ ruthenium catalyst. Initial studies were focused on making fused bicyclic ring systems through tandem dienyne metathesis in a single step. However, We discovered that this strategy had only a limited success. So our strategy was changed to stepwise ring-closing metathesis. Several bicyclic systems were easily obtained by catalytic ring-closing metathesis. Most of the substrates were successful and their yields were good.