Preparation of trans‐octaethylchlorin‐D2(α,β),‐D2(γ,δ), and ‐d4 as well as octaethylporphyrin‐d2 using acid‐catalyzed exchange reaction

Abstract

AbstractPreparation of three forms of selectively deuterated trans‐octaethylchlorin (t‐OEC) and octaethylporphyrin‐d2 (OEP‐d2) with high isotopic purity using acid catalyzed hydrogen‐deuterium exchange reaction is described. Deuterated t‐OEC labeled at γ,δ‐methine carbons was prepared directly by equilibrating t‐OEC in D2SO4:D2O (6:1, v/v) at room temperature for 20 hours. t‐OEC labeled at all four methine carbons was prepared as above in 72 hours. And t‐OEC labeled at α,β‐positions was obtained by “back‐exchange” of t‐OEC‐d4 under the protio condition, H2SO4:H2O (6:1, v/v), in 18 hours. The DDQ dehydrogenation of either dideuterochlorin species resulted in the formation of OEP‐d2. The isotopic purities of all deuterated compounds were over 98 percent except for t‐OEC‐d2(α,β) which was estimated to be ∼ 90 percent by proton NMR spectroscopy.