An Experimental and Theoretical Study on the Interaction of <i>N</i>-Heterocyclic Carbene-Derived 1,3-Dipoles with Methoxycarbonylallenes: Highly Regio- and Stereoselective [3+2]-Cycloadditions Controlled by the Structures of <i>N</i>-Heterocycles of 1,3-Dipoles
N-heterocycles of 1,3-dipoles. In addition, the reaction temperature played an important part in regulating the regioselectivity of [3+2]-cycloaddition in some cases. While the reactionbetween benzimidazole carbene-derived 2-thiocarbamoyl benzimidazolium inner salts 5 and methoxycarbonylallenes 6 with or without heating gave predominantly adducts of C+−C−S− moiety to the alkyl-substituted double bond