Unprecedented visible light-initiated topochemical [2 + 2] cycloaddition in a functionalized bimane dye

• Metodej Dvoracek,
• Brendan Twamley,
• Mathias O. Senge and
• Mikhail A. Filatov

Beilstein J. Org. Chem. 2025, 21, 500–509, doi:10.3762/bjoc.21.37

• with the Schmidt criteria for topochemical cycloaddition. Additionally, two other bimane derivatives with different substitution patterns were synthesized and investigated. Our findings suggest that functionalizing bimanes to redshift their absorption maxima into the visible-light spectrum provides a

• promising strategy for synthesizing substituted cyclobutanes without the need for ultraviolet irradiation. Keywords: bimane; [2 + 2] cycloaddition; fluorescence; topochemical polymerization; X-ray crystallography; Introduction Topochemical polymerizations refer to polymerization reactions occurring in the

• development of a novel scaffold for topochemically active monomers. Bimanes Bimanes, a class of bicyclic compounds first synthesized by Kosower and Pazhenchevsky in 1978 [16], are based on a 1H,7H-pyrazolo[1,2-a]pyrazole-1,7-dione scaffold. The general structure of a bimane is depicted in Figure 1a. The term