4-Azidocinnoline-Cinnoline-4-amine Pair as a New Fluorogenic and Fluorochromic Environment-Sensitive Probe

A new type of fluorogenic and fluorochromic probe based on the reduction of weakly fluorescent 4-azido-6-(4-cyanophenyl)cinnoline to the corresponding fluorescent cinnoline-4-amine was developed. We found that the fluorescence of 6-(4-cyanophenyl)cinnoline-4-amine is strongly affected by the nature of the solvent. The fluorogenic effect for the amine was detected in polar solvents with the strongest fluorescence increase in water. The environment-sensitive fluorogenic properties of cinnoline-4-amine in water were explained as a combination of two types of fluorescence mechanisms: aggregation-induced emission (AIE) and excited state intermolecular proton transfer (ESPT). The suitability of an azide-amine pair as a fluorogenic probe was tested using a HepG2 hepatic cancer cell line with detection by fluorescent microscopy, flow cytometry, and HPLC analysis of cells lysates. The results obtained confirm the possibility of the transformation of the azide to amine in cells and the potential applicability of the discovered fluorogenic and fluorochromic probe for different analytical and biological applications in aqueous medium.

Synthesis of highly substituted tetrahydroquinolines using ethyl cyanoacetate via aza-Michael-Michael addition

A three-component cascade reaction involving 2-alkenyl aniline, aldehydes, and ethyl cyanoacetate in the presence of DBU to synthesize highly substituted 1,2,3,4-tetrahydroquinolines is reported. The reaction proceeded through the Knoevenagel condensation of ethyl cyanoacetate with aldehydes followed by the aza-Michael-Michael addition with 2-alkenyl anilines to prepare the tetrahydroquinoline scaffolds.

Synthesis of 5-Amino-2,5-dihydro-1H-benzo[b]azepines Using a One-Pot Multibond Forming Process

Rapid access to allylic trichloroacetimidates bearing a 2-allylaminoaryl group from readily available 2-iodoanilines combined with a one-pot multibond forming process has allowed the efficient synthesis of a series of 5-amino-2,5-dihydro-1H-benzo[b]azepines. The potential of these compounds as synthetic building blocks was demonstrated by the preparation of a late-stage intermediate of the hyponatremia agent, mozavaptan.

A Pd(ii)-catalyzed C–H activation approach to densely functionalized N-heteroaromatics related to neocryptolepine and their evaluation as potential inducers of apoptosis

Bioactive indoloquinolines are synthesized via Pd(ii)-catalyzed intramolecular oxidative C–H alkenylation as the key step.