To add the finishing touch, we decided to search for other traits that the new catalysts can exhibit owing to their small-NHC ligands and overall enhanced stability. To achieve this, we have selected diastereoselective ring-rearrangement metathesis (DRRM)-a transformation that has been applied in the synthesis of a number of fused carbocycles as well as N-and O-heterocycles and various natural products. According to our previous work, we used substrate 26 to check if sterically-reduced NHC ligand can influence the cis/trans selectivity of this transformation (Scheme 6A). We found that within the tested catalysts, Ru16 and Ru17 gave the highest stereoselection towards trans-27 (up to 2.8:1). Catalysts Ru3 and Ru2, bearing gradually enlarged symmetrical NHC ligands gave greater proportions of cis-isomer, and finally the SIPr-substituted catalyst Ru20 lead to a 1:1 mixture of cis and trans-27. A similar tendency was also observed by Blechert in his work .