Syntheses of per-15N labeled etioporphyrins I-IV and a related tetrahydrobenzoporphyrin for applications in organic geochemistry and vibrational spectroscopy

Syntheses of per-nitrogen-15 porphyrins from labeled sodium nitrite and glycine are described. The pyrrolic precursors were prepared by the Knorr, Kleinspehn, and Barton-Zard condensations. per-15N etioporphyrin-I was prepared via pyrromethene intermediates, while per-15N etioporphyrins II-V and a related tetrahydrobenzoporphyrin were synthesized by the copper(II) mediated cyclization of a,c-biladiene intermediates.