Sc-Catalyzed Asymmetric [2 + 2] Annulation of 2-Alkynylnaphthols with Dienes to Access Cyclobutene Frameworks.

Herein, we introduce a scandium-catalyzed synthetic strategy that provides access to a diverse and functionalized array of cyclobutene frameworks adorned with a quaternary carbon center. This approach broadens the synthetic repertoire of 2-alkynylnaphthols with alkenes, offering a versatile platform for the construction of complex molecular architectures. The asymmetric catalytic [2 + 2] cycloaddition reaction demonstrates a wide substrate scope and an impressive functional group tolerance, yielding products with high efficiency, up to 97% yield, and excellent enantiomeric excess of up to 97%.

Highly Chemoselective [2+1] Annulation of α-Alkylidene Pyrazolones with α-Bromonitroalkenes: Synthesis of Pyrazolone-Based Vinylcyclopropanes and Computational Studies.

A highly chemoselective [2+1] annulation of α-alkylidene pyrazolones with α-bromonitroalkenes has been achieved under mild conditions. α-Alkylidene pyrazolones were unprecedentedly used as a C1 synthon to participate in annulation reactions, providing access to diverse vinylcyclopropane-based pyrazolone products. In addition, a spectrum of pharmaceutically interesting pyrazole-fused pyranone oximes could be rapidly obtained through a [2+1] annulation/rearrangement sequential process.

Enantio- and diastereoselective synthesis of spiropyrazolones via an organocatalytic [1 + 2 + 3] multicomponent reaction.

An asymmetric catalytic multicomponent reaction of malononitrile, benzaldehyde, and α-arylidene pyrazolinones to produce spiropyrazolones has been reported. The [1 + 2 + 3] multicomponent reaction was catalyzed by chiral cinchona alkaloids to provide spiropyrazolones in high yields, with excellent enantioselectivities and good diastereoselectivities. We also performed control experiments and proposed a plausible catalytic cycle based on the observed experimental results to explain the reaction process and stereoselectivity of the asymmetric multicomponent reaction.

Chemo- and Stereoselective Cross Rauhut-Currier-Type Reaction of Tri-substituted Alkenes Containing Trifluoromethyl Groups.

A chemoselective cross Rauhut-Currier-type reaction has been developed involving a tri-substituted alkene (trifluoromethyl-containing acrylonitrile derivative) with a di- or tri-substituted alkene to yield tetra-substituted double bonds in RC-type products. This approach can support the synthesis of trifluoromethylated tetra-substituted olefins and synthetically important, structurally complex 3-allylic-type oxindole skeletons. The asymmetric version of this RC-type reaction can be realized by combining a Brønsted acid and Lewis base for bifunctional H-bonding-tertiary amine catalysis.

Efficient sample clean-up and online preconcentration for sensitive determination of melamine in milk samples by capillary electrophoresis with contactless conductivity detection.

Based on an efficient sample clean-up and field-amplified sample injection online preconcentration technique in capillary electrophoresis with contactless conductivity detection, a new analytical method for the sensitive determination of melamine in milk samples was established. In order to remove the complex matrix interference, which resulted in a serious problem during field-amplified sample injection, liquid-liquid extraction was utilized. As a result, liquid-liquid extraction provides excellent sample clean-up efficiency when ethyl acetate was used as organic extraction by adjusting the pH of the sample solution to 9.

A new Neotyphodium species from Festuca parvigluma Steud. grown in China.

Neotyphodium species evolved from Epichloë species and are asexual, seedborne endophytes in many cool-season grasses. Here we propose a new species inhabiting Festuca parvigluma native to China. Morphology, host specificity and molecular phylogenetic evidence supported recognition of this new species.

A new stromata-producing Neotyphodium species symbiotic with clonal grass Calamagrostis epigeios (L.) Roth. grown in China.

We describe a new stromata-producing Neotyphodium species symbiotic with clonal Calamagrostis epigeios (L.) Roth. Stromata on the grass, 47.

A new species of Epichloë symbiotic with Chinese grasses.

Epichloë species are fungal symbionts (endophytes) of grasses, six European and four North American biological species in genus Epichloë have been described in previous researches. In this study we describe a new Epichloë species, Epichloë yangzii Li et Wang, found in natural symbioses with Roegneria kamoji native to China. We investigated the host specificity, morphology, interfertility tests and molecular phylogenetic evidences of this new species.