Synthesis, Crystal Structure, Antioxidant Activity of Chalcones and Its Spiro-heterocyclic Analogues

To synthesize new structure type chalcone analogues, and obtain chalcone analogues with good antioxidant activity. Two types of chalcone analogs, chalcones A and spiro-heterocyclic B were designed and synthesized, and the structures of 21 compounds were characterized by H-1 NMR, ESI-MS and ESI-HRMS. Single-crystal of spiro-heterocyclic B was cultured, and its single-crystal structure was determined by X-ray diffraction study. The crystal structure of B1 was monoclinic system, space group C2/c, with cell dimensions of a=21.350(3) angstrom, b=8.6256(10) angstrom, c=26.161(3) angstrom. Spiro-heterocyclic B is the new structure type, and obtained by one-pot synthesis which is 1,3-dipolar cycloaddition reaction and no catalyst. The synthesis of spiro-heterocyclic B is not only high regioselectivity and stereoselectivity, but also environmentally friendly. The antioxidant activities in vitro were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Many compounds, which can have strong activity of scavenging DPPH free radicals, were screened. In the 2 types of chalcones analogs, the compounds with 3,4-(OH)(2) in "a" ring have excellent antioxidant activities. The chalcone analogs with o-dihydroxy in benzene ring maybe have good antioxidant activities.