We have successfully established an efficient catalytic system, which was effective for construction of both spiro[pyrrolidinebenzofuran-3-one] and spiro[pyrrolidine-benzofuran-2-one] compounds. The first 1,3-dipolar cycloaddition of 2-alkylidenebenzofuran-3-one with azomethine ylides with simple functional ionic liquids as catalysts was developed, affording a variety of spiro[pyrrolidine-benzofuran-3-one] compounds containing highly substituted pyrrolidine motifs with a spiro quaternary stereogenic center in excellent yields (73-99 %). The highly efficient catalytic system exhibited broad substrate scopes under mild conditions. Meanwhile, this catalytic system was also extended to the cycloaddition of 3-alkylidene-benzofuran-2-one with azomethine ylides and gave spiro[pyrrolidinebenzofuran-2-one] compounds in high yields (82-99 %) and 1,3-dipolar cycloaddition of 2-alkylidene-benzofuran-3-one with pyrazolidinone-based dipoles giving the desired products in 25-85 % yields.

The blood‑brain barrier (BBB) constitutes an efficient organization of tight junctions that limits the delivery of tumor to the brain. The principal tight junction protein in BBB is claudin‑5 (CLDN5), but its mechanism of action remains largely unknown. Long non‑coding RNAs (lncRNAs) are aberrantly expressed in many cancers, some lncRNAs play key roles in regulating BBB permeability and are involved in tumor brain metastasis. In particular, lncRNAs can function as competing endogenous RNAs (ceRNAs). Herein, we investigated whether ceRNA dysregulation is associated with alterations of the level of CLDN5 in human brain vascular endothelial hCMEC/D3 cells. The Affymetrix Human Transcriptome Array 2.0 and Affymetrix GeneChip miRNA 4.0 Array were used to detect the expression levels of 2,578 miRNAs, 22,829 lncRNAs, and 44,699 mRNAs in pLL3.7‑CLDN5‑transfected and pLL3.7 control hCMEC/D3 cells. The distinctly expressed miRNAs, lncRNAs, and mRNAs were subjected to construction of miRNA‑lncRNA‑mRNA interaction network. A total of 41 miRNAs, 954 lncRNAs, and 222 mRNAs were found to be differentially expressed between the CLDN5‑overexpressing and control group. 148 lncRNA acting as ceRNAs were identified based on the miRNA‑lncRNA‑mRNA interaction network. The function of differential mRNA in the network was determined by GO and pathway analysis. The potential roles of the 27 ceRNAs were revealed, the possible biology functions of these regulatory ceRNAs mainly included tight junction, focal adhesion, cell‑cell adhesion, cell growth and apoptosis. The identified sets of miRNAs, lncRNAs and mRNAs specific to CLDN5‑overexpressing hCMEC/D3 cells were verified by quantitative real‑time RT‑PCR experiment. Our study predicts the biological functions of a multitude of ceRNAs associated with the alteration of CLDN5 in brain vascular endothelial cells. Our data suggest that these dysregulated ceRNAs, in conjunction with the high CLDN5 levels, could serve as useful targets of prevention of brain metastasis formation. Further studies are warranted to determine the role of these ceRNAs in facilitating the function of CLDN5 in brain‑tumor barrier.

The catalyst can be recycled and reused up to five times without significant loss of activity. -(HU, W.-Q.; CUI, Y.-S.; WU, Z.-J.; ZHANG, C.-B.; DOU, P.-H.; NIU, S.-Y.; FU*, J.-Y.; LIU, Y.; RSC Adv. 5 (2015) 87, 70910-70914, http://dx.