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An efficient and more sustainable one-step continuous-flow multicomponent synthesis approach to chromene derivatives
Citation:
Vaddula, B. R., S. Yalla, AND M. A. Gonzalez. An efficient and more sustainable one-step continuous-flow multicomponent synthesis approach to chromene derivatives. Journal of Flow Chemistry. Akadémiai Kiadó, Budapest, Hungary, 5(3):172-177, (2015).
Impact/Purpose:
Invited contribution - Special Feature on Continous Flow Processes This contribution demonstrates the integration of green chemistry and green engineering principles to arrive at a chemical synthesis route which is immediatley scalable and extremely selective, modular and provides high conversion. In addition, also demonstrates energy savings and offers potential for improved worker saftey and increased process economics.
Description:
A simple and rapid one-step continuous-flow synthesis route has been developed for the preparation of chromene derivatives from the reaction of aromatic aldehydes, α-cyanomethylene compounds and naphthols. In this contribution, a one-step continuous-flow protocol in a continuous flow reactor (ThalesNano H-Cube ProTM) has been developed for the preparation of these chromene derivatives. This arises from the multi-component one-step reaction of aromatic aldehydes, α-cyanomethylene compounds and naphthols. This flow protocol was optimized in 2-methyltetrahydrofuran, which is a more environment-friendly solvent. The faster residence times (< 2 min) experienced coupled with elevated pressure (~25 bar) results in an efficient, safer, faster and modular reaction. Results obtained illustrate this base-catalyzed reaction affords the respective chromene derivative products in almost quantitative yields. The products can then be easily purified by recrystallization, if desired.
