Microwave Synthesis of Water-Soluble 2-, 5-and 9-Substituted Benzo[a]phenoxazinium Chlorides in Comparison with Conventional Heating

作者：Firmino A Daniela G; Rama Raju B; Goncalves M Sameiro T^*

来源：European Journal of Organic Chemistry, 2013, 2013(8): 1506-1514.

DOI：10.1002/ejoc.201201354

• Synthetic methods
• Dyes/pigments
• Fluorescent probes
• Microwave chemistry

Microwave irradiation was used for the first time in an efficient synthesis of benzo[a]phenoxazinium chlorides. The main advantage of this protocol is the notable reduction in reaction times and good to excellent yields of the products in comparison to those obtained under classical heating conditions. These new series of compounds possess 5-amine and/or 2-hydroxyl substituents in the polycyclic system to improve their solubility in aqueous media, in addition to the functional groups as terminals in the side chains, allowing their further use in covalent labeling. Fundamental photophysical studies carried out in ethanol and water at physiological pH revealed that all cationic fluorophores absorbed and emitted at 610-628 and 630-652 nm, respectively, with relative fluorescent quantum yields of 0.16-0.96.

• 出版日期2013-3