A novel general method for fast and easy preparation of cationic, neutral dimethinehemicyanine and dimethine dyes by uncatalysed Knoevenagel condensation

Abstract

Three novel general experimental procedures for preparation of cationic, neutral dimethinehemicyanine and dimethine dyes (eight of which are unpublished) by uncatalysed Knoevenagel condensation have been developed. The proposed methods are versatile as a variety of different starting materials can be used and they ensure good to very high yields, very short reaction times and high purity of the final dyes. Absorption and fluorescent properties of the novel dyes were investigated.

Recent Advances in the Use of Glycerol as Green Solvent for Synthetic Organic Chemistry

“…Similarly, broad series of push-pull styryl dyes (some representative examples are shown in Figure 1) have been prepared in glycerol by Deligoergiev and co-workers through uncatalyzed condensations between aromatic aldehydes and N-alkylated salts of 2-methylazoles, 2-methylthiazoles, 2-methyloxazoles or 4-methylpyridine derivatives [52]. Condensation of α-bromoketones with thiourea/thioamide compounds also occurred rapidly in glycerol, under mild reaction conditions (r.t.) and without using any catalyst, to generate the corresponding substituted thiazole derivatives 10 with high yields and selectivity (Scheme 9) [53].…”

Synthesis, crystal structures, and spectral properties of double N-alkylated dimethine cyanine dyes and their interactions with biomolecules and living cells

“…Abd El-Aal et al 26 synthesized bsubstituted dimethine cyanine dyes, and discussed the relationship between the properties and structures of the dyes. Deligeorgiev et al 27 described three new general procedures for the synthesis of dimethine cyanine dyes using uncatalysed Knoevenagel condensation, which had several virtues, such as high yields, highly pure nal dyes, short reaction time and an environmentally friendly method, and investigated the spectral properties of the novel dyes. In previous work, 23,28 we synthesized a series of dimethine cyanine dyes and investigated, both experimentally and theoretically, the absorption and uorescence properties of these dyes.…”