Development and evaluation of a solid-supported cyclobutadieneiron tricarbonyl complex for parallel synthesis applications.

Cycloadditions of cyclobutadiene can offer rapid access to rigid polycyclic ring systems. Further functionalization of these strained-ring cycloadducts can lead to unique scaffolds for probing unexplored regions of chemical space. Along these lines, opportunities for high-throughput syntheses of these novel systems could be facilitated with the introduction of an immobilized cyclobutadiene reagent. Reported herein are preliminary studies of an iron tricarbonyl cyclobutadiene complex attached to solid support. Oxidative unmasking of the immobilized cyclobutadiene in the presence of various dienophiles is shown to produce a small collection of substituted bicyclo[2.2.0]hexene derivatives. The solid support cycloaddition strategy is shown to be comparable, but lower in efficiency to solution phase methods for generating these cycloadducts.