A phosphine-promoted tandem Diels-Alder reaction using pentadienyl 4-nitrobenzoate (α-vinyl MBH adduct) as a diene precursor with 3-olefinic oxindoles or CF-activated ketones as dienophiles has been developed. The reaction proceeds through the formation of a pentadienyl phosphonium intermediate via S2'' addition, which acts as both a D-A diene and a precursor for the exomethylene moiety. This method offers a metal-free and step-efficient approach for synthesizing exomethylene-bearing spirooxindoles and dihydropyrans, which are privileged structures found in natural products.
View Article and Find Full Text PDFXi Bao Yu Fen Zi Mian Yi Xue Za Zhi
May 2012
Aim: To investigate the protective effect and mechanism of curcumin against ActD/TNF-α-induced synergistically apoptosis in PC12 cells.
Methods: MTT assay was used to evaluate the optimal concentration of drugs; Hoechst 33258 fluorescent staining to observe apoptosis of PC12 cells, JC-1 was used to detect the mitochondrial membrane potential (MMP), real-time PCR was used to detect the expression of two apoptotic genes: Bcl-1 and Bax.
Results: ActD/TNF-α can synergistically reduce viability of PC12 cells(P<0.