An efficient solvent free Amberlite IRA-400 Cl resin mediated multicomponent synthesis and photophysical properties of fluorescent 4 H -chromene derivatives
An efficient Amberlite IRA-400 Cl basic anion exchange resin mediated multicomponent reaction of 2-hydroxybenzaldehydes, 1, 3-diketone and nucleophiles under neat condition afforded a number of fluorescent 4H-chromenederivatives in excellent yield. The structure of the synthesized compounds 4k and 4u were confirmed from single crystal XRD studies. 4H-Among the chromene derivatives, compound 4v synthesized
Nanocrystalline and Reusable ZnO Catalyst for the Assembly of Densely Functionalized 4<i>H</i>-Chromenes in Aqueous Medium via One-Pot Three Component Reactions: A Greener “NOSE” Approach
作者:Partha Pratim Ghosh、Asish R. Das
DOI:10.1021/jo400763z
日期:2013.6.21
An ecofriendly, One-pot, three component ZnO nanoparticles-mediated synthesis of 4H-chromene in water under thermal condition has been described. The highly product-selective three component electrophilic reaction of 2-hydroxybenzaldehyde with an active methylene compound and another carbon-based varied nature of nucleophile has been developed by a reversible alkylation procedure using greener "NOSE" approach. Greenness of the process was well instituted, as water was used both;as reaction media as well as medium for the synthesis of catalyst. In these reactions, the use of nano-ZnO as a catalyst was documented to be crucial for rendering the reactions possible in water media, while replacing nano-ZnO with other acids or bases resulted in the generation of too many side products. The catalyst can be efficiently recycled up to the sixth run, an essential point in the area of green chemistry. The methodology provides cleaner conversion, shorter reaction times, and high selectivity, which make the protocol globally putative. The crystal structures of 4H-chromene, easily produced by a chromatography-free highly product-selective reaction, were explored by means of single crystal X-ray diffraction analysis, and H-bonding arrangements of one signified compound prepared is presented. In optimized mild conditions, the isolated yields are 86-93%.