Methine dyes comprising first and second nuclei joined by a double bond or a methine linkage. The first nuclei may be either A. a pyrido nucleus joined at the 4- or 6-carbon atom thereof to said double bond or methine linkage or, B. a 5,6-dihydropyrido nucleus joined at the 4- or 5-carbon atom to said double bond or methine linkage. The pyrido or dihydropyrido nucleus can have fused to its 1,2-side the atoms required to complete a ring containing 5 or 6 atoms. The second nuclei may be either the same as (a) or (b) or can be of the type typically used in cyanine styryl and merocyanine dyes. Such dyes are useful filter dyes and spectral sensitizers for silver halide compositions. Also described are intermediates useful in the synthesis of said dyes.
A new synthetic strategy for direct C(sp3)–H amination of carbonyl compounds at their α-carbon has been established employing molecular iodine and nitrogen-directed oxidative umpolung. In this transformation, iodine acts not only as an iodinating reagent but also as a Lewis acid catalyst, and both the nitrogen-containing moiety and the carbonyl group in the substrate play important roles. This synthetic