Methine and polymethine dyes containing at least one 2,6-diphenyltelluropyrylo group as well as another 2,6-diphenylchalcogenopyrylo group have been prepared by the condensation of 2,6-diphenyI-4-methylchalcogenopyrylium, salts with 4/7-2,6-diphenyltelluropyran-4-one or (4/7-2,6-diphenyltelluropyran-4-ylidene)acetaldehyde or by the reaction of 2,6-diphenyl-4-metiiyltelluropyrylium tetrafluoroborate with bisaldehyde equivalents. Similarly, various iVJV-dialkylamino-containing telluropyrylium dyes have also been prepared. The telluropyrylium dyes absorb at longer wavelengths than their oxygen, sulfur, or selenium counterparts. This shift can be empirically correlated with an increase in electropositive character of the heteroatom.

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Simple enamines derived from acetaldehyde, acetone, and propionaldehyde were generated in situ by iodine oxidation of triethylamine, V,iV-diisopropylmethylamine, and tri-n-propylamine, respectively. The enamines were captured by a variety of cationic substrates including trityl, indolizinium, dithiolium, pyrylium, thiapyrylium, selenapyrylium, and tellurapyrylium cations. The use of a second equivalent of iodine (or excess) oxidized the initial products of enamine capture to various iminium dyes. These dyes were easily hydrolyzed to heterocyclylidene aldehydes and ketones. Cyclic amines such as jV-methylpyrrolidine gave enamines derived from ring oxidation. 2-Cyano-NJV-dimethylethylamine generated a cyano-substituted enamine under the reaction conditions.

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