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PIWI-interacting RNAs (piRNAs) are small non-coding transcripts that are highly conserved across species and regulate gene expression through pre- and post-transcriptional processes. piRNAs were originally discovered in germline cells and protect against transposable element expression to promote and maintain genome stability. In the recent decade, emerging roles of piRNAs have been revealed, including the roles in sterility, tumorigenesis, metabolic homeostasis, neurodevelopment, and neurodegenerative diseases. In this review, we summarize piRNA biogenesis in C. elegans, Drosophila, and mice, and further elaborate upon how piRNAs mitigate the harmful effects of transposons. Lastly, the most recent findings on piRNA participation in neurological diseases are highlighted. We speculate on the mechanisms of piRNA action in the development and progression of neurodegenerative diseases. Understanding the roles of piRNAs in neurological diseases may facilitate their applications in diagnostic and therapeutic practice.

Palladium-catalyzed asymmetric formal [3 + 2] cycloaddition of vinyl cyclopropanes and aldimines or isatinderived ketimines proceeded smoothly in the presence of chiral phosphoramidite ligands. The corresponding highly functionalized and optically enriched pyrrolidine or spiro-[pyrrolidin-3,2′-oxindole] derivatives are obtained in up to 94% yield and with up to 96% ee and 7:1 dr.

A metal-dependent and complementary catalytic method to synthesize the cyclohexadienes has been developed. When gold or indium salts were used as catalysts, 1,3-cyclohexadiene (1,3-CHD) could be obtained; when Cu(OTf)2 was used as the catalyst, however, another isomer 2,4-cyclohexadiene (2,4-CHD) was furnished instead.

No abstract