Selective synthesis of enol ethers via nickel-catalyzed cross coupling of α-oxy-vinylsulfones with alkylzinc reagents.

We describe here a Ni-catalyzed Negishi coupling reaction to prepare 1,2-dialkyl enol ethers in a stereoconvergent fashion. This method employs readily available and bench-stable α-oxy-vinylsulfones as electrophiles. The C-sulfone bond in the α-oxy-vinylsulfone motif is cleaved chemoselectively in these reactions. The mild conditions are tolerant of a variety of functional groups on both partners, thus representing a general strategy for enol ether synthesis. This unique reactivity of α-oxy-vinylsulfones indicates their further application as electrophilic partners in cross-coupling reactions.

Nonenzymatic Stereoselective S-Glycosylation of Polypeptides and Proteins.

Here we report a nonenzymatic glycosylation reaction that builds axial S-glycosidic bonds under biorelevant conditions. This strategy is enabled by the design and use of allyl glycosyl sulfones as precursors to glycosyl radicals and exploits the exceptional functional group tolerance of radical processes. Our method introduces a variety of unprotected glycosyl units to the cysteine residues of peptides in a highly selective fashion. Through developing the second-generation protocol, we applied our method in the direct glycosylation of complex polypeptides and proteins. Computational studies were performed to elucidate the reaction mechanism.

Conducting Concurrent Electroencephalography and Functional Near-Infrared Spectroscopy Recordings with a Flanker Task.

Concurrent EEG and fNIRS recordings offer an excellent opportunity to gain a full understanding of the neural mechanism of cognitive processing by inspecting the relationship between the neural and hemodynamic signals. EEG is an electrophysiological technology that can measure the rapid neuronal activity of the cortex, whereas fNIRS relies on the hemodynamic responses to infer brain activation. The combination of EEG and fNIRS neuroimaging techniques can identify more features and reveal more information associated with the functioning of the brain. In this protocol, fused EEG-fNIRS measurements were performed for concurrent recordings of evoked-electrical potentials and hemodynamic responses during a Flanker task. In addition, the critical steps for setting up the hardware and software system as well as the procedures for data acquisition and analysis were provided and discussed in detail. It is expected that the present protocol can pave a new avenue for improving the understanding of the neural mechanisms underlying various cognitive processes by using the EEG and fNIRS signals.

Altered Functional Connectivity in the Motor and Prefrontal Cortex for Children With Down's Syndrome: An fNIRS Study.

Children with Down's syndrome (DS) might exhibit disrupted brain functional connectivity in the motor and prefrontal cortex. To inspect the alterations in brain activation and functional connectivity for children with DS, the functional near-infrared spectroscopy (fNIRS) method was applied to examine the brain activation difference in the motor and prefrontal cortex between the DS and typically developing (TD) groups during a fine motor task. In addition, small-world analysis based on graph theory was also carried out to characterize the topological organization of functional brain networks. Interestingly, behavior data demonstrated that the DS group showed significantly long reaction time and low accuracy as compared to the TD group (p < 0.05). More importantly, significantly reduced brain activations in the frontopolar area, the pre-motor, and the supplementary motor cortex (p < 0.05) were identified in the DS group compared with the TD group. Meanwhile, significantly high global efficiency (E g ) and short average path length (L p ) were also detected for the DS group. This pilot study illustrated that the disrupted connectivity of frontopolar area, pre-motor, and supplementary motor cortex might be one of the core mechanisms associated with motor and cognitive impairments for children with DS. Therefore, the combination of the fNIRS technique with functional network analysis may pave a new avenue for improving our understanding of the neural mechanisms of DS.