Simple approach to "locked" chlorins.
[reaction: see text] A novel synthetic approach to diversely functionalized "locked" chlorins is described. A suitably substituted 2,5-diformylpyrrole undergoes the macrocyclization reaction with tripyrranes, thereby generating porphyrins. Upon the reaction with 1,3-dipoles these porphyrins regioselectively furnish pyrrolidine-fused chlorins, which cannot oxidize to the corresponding porphyrins. In the process involving just six steps from commercially available and cheap materials we are able to obtain approximately 200 mg of pure stable chlorins (the overall yield is 1.5-2.8%).
Gryko
Daniel T
DT
Institute of Organic Chemistry of the Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland. daniel@icho.edu.pl
Gałezowski
Michał
M