An attempt has been made in order to unify the three types of solvatochromisms (negative, positive and inverted) of phenolate betaine dyes by a working model which describes them as particular cases of a general behavior. The model, based on the calculation (gas phase) of the chemical hardness of donor and acceptor fragments, was applied to 56 examples from the literature. As a result, the investigated compounds were grouped according to the sum of the hardnesses of their (non-interacting) fragments, this sum being larger for a negative, intermediate for an inverted, and smaller for a positive solvatochromic behavior.

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SummaryAn extension of the substrate scope of the Flögel-three-component reaction of lithiated alkoxyallenes, nitriles and carboxylic acids is presented. The use of dicarboxylic acids allowed the preparation of symmetrical bis(β-ketoenamides) from simple starting materials in moderate yields. Cyclocondensations of these enamides to 4-hydroxypyridine derivatives or to functionalized pyrimidines efficiently provided symmetrically and unsymmetrically substituted fairly complex (hetero)aromatic compounds containing up to six conjugated aryl and hetaryl groups. In addition, subsequent functionalizations of the obtained heterocycles by palladium-catalyzed couplings or by oxidations are reported. We also describe the simple synthesis of a structurally interesting macrocyclic bispyrimidine derivative incorporating a 17-membered ring, whose configuration was elucidated by DFT calculations and by subsequent reactions.