The triphenylmethyl group can be used as a steric buttress to drive otherwise unfavorable
intramolecular Diels-Alder cycloaddition reactions. Using this strategy, we attempted to
synthesize the cycloadducts 9-triphenylmethylaza-1,4-oxidobicyclo[4.4.0]dec-2-ene (3b) and 10-triphenylmethylaza-1,4-oxidobicyclo[5.4.0]undec-2-ene (3c) from furfurylamine-based starting
materials, and it was found that the presence of the buttress was not sufficient to promote the
formation of 3c, even with high temperatures and long reaction times. Density functional theory
calculations on the reaction system provide insight into the nature of the trityl group’s effect on
the thermodynamics of the cycloaddition reaction, and indicate that the trityl group exhibits
equally important kinetic and thermodynamic driving effects.