Phosphine-Promoted Tandem Intermolecular Diels-Alder Reactions with Pentadienyl 4-Nitrobenzoate as a Diene Precursor.

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.

[Protective effect and mechanism of curcumin on ActD/TNF-α-induced synergistically apoptosis in PC12 cells].

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.