Herein we describe a combined experimental/theoretical study on the effects of substituents on regio- and stereoselectivity in intramolecular 1,3-dipolar cycloadditions of nitrones and alkenes tethered by benzimidazoles. By employing a large substituent at position R2 or R3, complete selectivity was achieved for either the fused or bridged cycloadduct, respectively. In addition, these cycloadducts were formed as single diastereomers in all of the cycloadditions examined.
Keywords: Dipolar cycloaddition; Nitrone; Quantum chemical calculations; Stereoselectivity; Substituent effects.