Synthesis of hydrodipyrrins tailored for reactivity at the 1- and 9-positions

A collection of 33 hydrodipyrrins (9 targets, 21 intermediates, and 3 byproducts) has been prepared. The hydrodipyrrins (dihydrodipyrrins, tetrahydrodipyrrins, and hexahydrodipyrrins) contain a pyrrole ring and a geminal-dimethyl substituted 1-pyrroline (or pyrrolidine) ring. The α-substituents on the pyrrole ring (H, Br, CHO) and pyrroline ring (H, CH3, CH(OR)2, OMe, SMe) provide different reactivity combinations (Nu−, E+) and 0, 1, or 2 carbon atoms (which can give rise to the bridging meso-carbons in hydroporphyrins). Straightforward access to various hydrodipyrrins should facilitate development of syntheses of diverse hydroporphyrins.