404, 585, and 635 mp (log E,,, ca. 5.08, 4.30, and 4.48)) was formed. If the cyclization was carried out with methyl orthoformate-trichloroacetic acid, and followed by aeration without added base, a green compound ( A , , , 404 and 700 mp (log emax ca. 5.00 and 4.48)) was formed, which readily changed into VI1 or its salts ( Me \"\" 'Me 209 (1938), has very similar visible absorption. We favor the keto structure VII, which would gain aromaticity from dipolar character, but the tautomeric hydroxy structure is not excluded.( 1 1 ) meso-Monomethylaetioporphyrins likewise have, e.g., A, , , 408, 505, 539, 579, and 630 mp (log e 5.