Three Complementary One‐Pot Four‐Component Reaction Sequences for Rapid, General and Direct Spiropyran Synthesis

Abstract

Three one-pot three-step four-component reaction sequences for spiropyran synthesis have been developed, based around three different methods for in situ generation of 1,2,3trisubstituted indoles (indole N-alkylation, Fischer indolisation and indole C-alkylation). The reaction sequences give access to a broad swathe of spiropyran structures. Each sequence is operationally straightforward, rapid and high yielding. We have synthesized 58 structurally diverse spiropyrans bearing a wide range of useful functional groups, and their utility were demonstrated in the targeted synthesis of potential ratiometric fluorescence probes for metal ions and spiropyran-cholesterol conjugates. Finally, we showed that our one-pot N-alkylation-Calkylation-condensation sequence can underpin combinatorial spiropyran synthesis through generation of a 16-member spiropyran library.

Fluorescent Materials Based on Spiropyran for Advanced Anti-Counterfeiting and Information Encryption

“…Ongoing research efforts continue to explore novel synthetic strategies and to optimize their properties further, aimed at unlocking even more exciting applications in areas such as smart materials or advanced photonics technologies. There are a number of studies reporting on the synthesis of spiropyran compounds [ 25 , 26 , 27 , 28 , 29 ], and applications of spiropyran-based materials in fluorescent probes [ 30 , 31 , 32 , 33 , 34 , 35 ], advanced photoswitchable materials [ 36 , 37 , 38 , 39 , 40 ], and bioimaging [ 41 , 42 , 43 , 44 , 45 , 46 ]. However, we found no review on the design of fluorescent materials based on spiropyran for anti-counterfeiting.…”