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Pd-catalyzed stereoselective glycosylations using unsaturated sugar derivatives, glycals, have been successfully achieved in recent years. This review focuses on approaches to control the stereoselectivities of glycosides via π-allyl intermediates that mimic the Tsuji-Trost asymmetric allylic alkylation reactions, enabling stereoselectivity control through rational design. In the reaction process, zwitterionic Pd-π-allyl complexes, formed after the oxidative addition and decarboxylation, play a crucial role in increasing reactivities and enhancing the stereoselectivities of α- and ß-glycosides. We summarized recently developed Tsuji-Trost type glycosylations using 3,4-carbonate galactals, featuring high efficiency, exclusive stereoselectivities, and a broad reaction scope including O-, N-, S-, and C-glycosylations.
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A Rh(II)-catalyzed furyl carbene N-H insertion reaction involving an N-sp2-hybridized imine is described, which represents an atom-economical route by which to access diarylmethylamine derivatives with high efficiency and broad substrate scope. An unusual reaction mechanism is proposed, in which the rhodium catalyst plays a dual role in facilitating enynone cyclization via activation and enhancement of the nucleophilicity of the NH imine.
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A simple transition metal-free strategy for the synthesis of pyrido[1,2-a]indolone derivatives has been devised through sodium methoxide-catalyzed intramolecular cyclization of 2-alkenylated N-pyrimidyl indoles. The reactions involved a Smiles rearrangement/cyclization cascade, which resulted in a new series of N-fused indoles, potentially applicable skeletons in medicinal chemistry. This reaction presents simple eco-friendly reaction conditions, a high atom- and cost-economy, a short reaction time, and a broad range of substrate scope with high reaction efficiency.
Assuntos
Elementos de Transição , Catálise , Ciclização , IndóisRESUMO
To investigate whether the defects in transient receptor potential canonical 4 (TRPC4), which is strongly expressed in the hippocampus, are implicated in ASD, we examined the social behaviors of mice in which Trpc4 was deleted (Trpc4-/-). Trpc4-/- mice displayed the core symptoms of ASD, namely, social disability and repetitive behaviors. In microarray analysis of the hippocampus, microRNA (miR)-138-2, the precursor of miR-138, was upregulated in Trpc4-/- mice. We also found that binding of Matrin3 (MATR3), a selective miR-138-2 binding nuclear protein, to miR-138-2 was prominently enhanced, resulting in the downregulation of miR-138 in Trpc4-/- mice. Some parameters of the social defects and repetitive behaviors in the Trpc4-/- mice were rescued by increased miR-138 levels following miR-138-2 infusion in the hippocampus. Together, these results suggest that Trpc4 regulates some signaling components that oppose the development of social behavioral deficits through miR-138 and provide a potential therapeutic strategy for ASD.
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An atom-economical strategy for the C-H alkenylation and C-H allylation of arenes by employing cyclopropenes as versatile alkenylating and allylating reagents is reported, catalyzed by cobalt. The Co-catalyzed C-H alkenylation process involves sequential C-H and C-C bond cleavage. Under the optimized conditions, broad-ranging alkenylated (hetero)arenes were synthesized with complete (E)-stereoselectivity (up to 91%). The consecutive C-H allylation proved viable under basic conditions via double-bond migration of the initially generated alkenyl (hetero)arenes, thus leading to allylated (hetero)arenes with high stereoselectivity of olefin (E/Z ratio = 91:9 to 100:0).