The free-base and Zn(II) complexes of N-methyl-β-octaethyl- and meso-tetratolylchlorin and isobacteriochlorin were synthesized and characterized. Direct methylation of free-base hydroporphyrin compounds was unexpectedly selective. Only one of the several possible regioisomers that could result from alkylation of the inequivalent N atoms was produced for each hydroporphyrin free-base. This result was independent of the electrophilic reagent ([MeSPh2][BF4] for meso-tetraaryl compounds and methyl trifluoromethanesulfonate for β-octaethyl compounds) or the peripheral substituents on the hydroporphyrin. However, the greater basicity of the β-octaethyl substituted compounds resulted in their isolation as protonated cations. Methylation occurred at a pyrrole ring rather than a pyrroline ring. In chlorins, the pyrrole ring across the macrocycle from the pyrroline ring was methylated to afford the symmetric N-methyl chlorins H(s-N23-MeTTC) and H2(s-N23-MeOEC)+. The selectivity is a result of kinetic rather than th...

The Synthesis, Properties, and Reactivities of Free-Base- and Zn(II)-N-Methyl Hydroporphyrin Compounds. The Unexpected Selectivity of the Direct Methylation of Free-Base Hydroporphyrin Compounds

James F. Rounsaville

Papers

Miscibility in the Systems Sodium Iodide-Trisodium Bismuthide and Sodium Iodide-Trisodium Antimonide