An efficient methodology was developed for the synthesis of multisubstituted spirocyclopropane derivatives. The reaction between isatin (acenaphthoquinone) and α-bromo(chloro)-acetophenone compounds afforded the corresponding spirocyclopropane products with high stereoselectivity via a one-pot tandem reaction in the presence of α-picoline and triethylamine. In addition, spirocyclopropanepyrazoles were obtained in good yields via a one-pot cascade reaction of α-bromo-acetophenone, pyrazolone and aromatic aldehydes. Diverse spirocyclopropane compounds were prepared through the multicomponent one-pot pathway. The high efficiency of this process and operational simplicity make it an attractive method for the synthesis of spirocyclopropanes.
Wei Wu,Yingcai Ding,Ping Xie,Qiujie Tang,Charles U. Pittman,Aihua Zhou
Structure containing the C S bond exist widely in nature, drugs and chemical materials . Here, a novel sulfenylation protocol employing an aryl or alkyl halide and odorless and cheap S as reagents was developed, generating regioselective alkyl-S- and Ar-S-substituted imidazol[1,2-α]pyridine derivatives in good yields under relatively environmentally friendly and mild conditions. This protocol enriches current thioether-producing methods, making up for the shortcomings of previous sulfenylation methods which can only make MeS- and ArS-substituted imidazol[1,2-α]pyridine derivatives.
Mei Han,Chunyuan Kang,Zexing Qu,Shoujun Zhu,Bai Yang
Current sunlight-powered H 2 production that employ carbonized polymer dots (CPDs)-graphitic carbon nitride (g-C 3 N 4 ) systems has made significant progress. However, we still have a limited understanding of the mechanism by which CPDs contribute to the phtocatalytic efficiency. Surface molecule 1,2,3,5-tetrahydro-5-oxo-imidazo[1,2- α ]pyridine-7-carboxylic acid (IPCA) has been verified to largely impact the photophysical properties of CPDs. Here, we report the design of g-C 3 N 4 , IPCA-g-C 3 N 4 and CPDs-g-C 3 N 4 catalysts to uncover the critical role of IPCA. The photocatalytic H 2 production rates of g-C 3 N 4 were improved by the hybridization with IPCA and CPDs (1172 ± 39; 2150 ± 92 vs. 828 ± 121 μmol g −1 h −1 , respectively). The DFT calculations further unraveled that electron transfer pathway in ICPA-CN@H 3 O + followed ICPA -> g-C 3 N 4 -> H 3 O + procedure. The results indicate that IPCA on CPDs is conducive to extending the light-responsive range, redistributing of photoinduced electron-hole pairs, increasing the electron density of g-C 3 N 4 , and thus improving H 2 generation rates.
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