Synthesis of Novel Key Chromophoric Intermediates via C-C Coupling Reactions

The fundamentals of Pd-catalyzed Csp2−Csp2 Miyaura borylation, Suzuki cross-coupling, and Stille cross-coupling reactions for a variety borylated precursors based on phenothiazine (PTZ), phenoxazine (POZ), carbazole (Cz), quinoxaline (QX) units have been explored. Three palladium-based catalysts were chosen this study: Pd(PPh3)4, Pd(PPh3)2Cl2, Pd(dppf)Cl2, applying different reaction conditions. Around 16 desired chromophores successfully designed synthesized using C-C in moderate to excellent yields, including PTZ, POZ, Cz coupled with QX, indolinium iodide, thienyl, phenyl, or triphenylamine moieties. Additionally, employed synthesizing various pinacol boronate ester derivatives good yields. Interestingly, Pd(dppf)Cl2 was found be the best catalyst occurred as little 30 min, an yield exceeding 98%. Pd(PPh3)4 Pd(PPh3)2Cl2 catalyzed obtain products yields after long time (20–24 h). On other hand, Suzuki-Miyaura between N-(2-methyl)hexyl derivative 10c three halogenated derivatives—4-(3-(5-bromothiophen-2-yl)quinoxalin-2-yl)benzaldehyde (27), 4-(5-(3-(5-bromothiophen-2-yl)quinoxalin-2-yl)thiophen-2-yl)benzaldehyde (30), 4-(3-chloroquinoxalin-2-yl)benzaldehyde (25) by Pd(PPh3)4—afforded carbazole-quinoxaline (28, 30, 31, respectively) 2–3 h, reaching 86%. electron-deficient QX couplers proved efficiently coupling reaction, which involves electron-rich orgaostannane halide. characterized FTIR, 1H-NMR, 13C-NMR, HRMS.