Pyryliumverbindungen. XXVII. Spezifisch deuterierte Carbo- und Heterocyclen via 2,4,6-Triaryl-[3,5-2H2]pyryliumsalze

Pyrylium Compounds. XXVIII. Specifically Deuterated Carbo- and heterocycles via 2,4,6-Triaryl[3,5-²H₂]pyrylium Salts On heating with catalytic amounts of bases(e.g. triethyl amine) in deuterated alcohols such as methan[²H]ol or ethan[²H]ol pseudobases of 2, 4, 6-triarylpyrylium salts 1 undergo fast¹H/²H isotopic exchange reaction affording 1, 3, 5-triaryl[2, 4, 4-²H₃]pent-2-ene-1,5-diones which with [²H] perchloric acid give highly deuterated 2, 4, 6-triaryl-[3, 5-²H] pyrylium perchlorates 8 . These salts are obtainable also directly from 1 through a one-pot procedure by ring opening of the latter with deuterium oxide under the above-mentioned¹H/²H isotopic exchange conditions followed by recyclization of the formed 1, 3, 5-triaryl[2, 4, 4-²H₃]pent-2-ene-1, 5-diones with [²H]ClO₄. Ring transformations of 2, 4, 6-triphenyl[3, 5-²H²]pyrylium perchlorate (8a) to 2, 4, 6-triphenyl[3, 5-²H₂]nitrobenzene (9) 2, 4, 6-triphenyl[3, 5-²H₂]pyridine (10) , 1, 2, 4, 6-tetraphenyl[3, 5-²H₂]pyrydinium perchlorate (11) , 2, 4, 6-triphencyl[3, 5-²H₂]thiopyrylium perchlorate (12) , 2-benzoyl-3, 5-diphenyl[4-²H]furan (13) , and 3, 5, 7-triphenyl-[4, 4, 6-²H₃]4H-1, 2-diazepin (14) demonstrate the usability of pyrylium salts of type 8 as starting materials for syntheses of specifically deuterated carbo- and hetrocycles.