From Quaternary Carbon to Tertiary C(sp3)-Si and C(sp3)-Ge Bonds: Decyanative Coupling of Malononitriles with Chlorosilanes and Chlorogermanes Enabled by Ni/Ti Dual Catalysis.

Transition-metal-catalyzed C-Si/Ge cross-coupling offers promising avenues for the synthesis of organosilanes/organogermanes, yet it is fraught with long-standing challenges. A Ni/Ti-catalyzed strategy is reported here, allowing the use of disubstituted malononitriles as tertiary C(sp3) coupling partners to couple with chlorosilanes and chlorogermanes, respectively. This method enables the catalytic cleavage of the C(sp3)-CN bond of the quaternary carbon followed by the formation of C(sp3)-Si/C(sp3)-Ge bonds from ubiquitously available starting materials. The efficiency and generality are showcased by a broad scope for both of the coupling partners, therefore holding the potential to synthesize structurally diverse quaternary organosilanes and organogermanes that were difficult to access previously.

Reductive Aza-Pauson-Khand Reaction of Nitriles.

γ-Lactams are valuable heterocycles in synthetic chemistry and drug development. Here, we report a reductive aza-Pauson-Khand reaction (aza-PKR) of an alkyne, a nitrile, and Co2(CO)8. A wide array of bicyclic α,ß-unsaturated γ-lactams containing two adjacent stereocenters, including an all-carbon quaternary center, from alkyne-tethered malononitriles are efficiently accessed in high diastereoselectivity. Preliminary mechanistic investigations by experiments and DFT calculations reveal that the reaction undergoes an aza-PKR process followed by a in situ reduction. The reducing reagent generated in situ from water also provides a practical tool for deuterium incorporation into the γ-position of lactams using D2O as the deuterium source. This study represents a new mode for [2 + 2 + 1] cycloaddition that enables the direct use of nitrile in aza-heterocycle synthesis.

Trifluoromethanesulfonyl azide as a bifunctional reagent for metal-free azidotrifluoromethylation of unactivated alkenes.

Vicinal trifluoromethyl azides have widespread applications in organic synthesis and drug development. However, their preparation is generally limited to transition-metal-catalyzed three-component reactions. We report here a simple and metal-free method that rapidly provides these building blocks from abundant alkenes and trifluoromethanesulfonyl azide (N3SO2CF3). This unprecedented two-component reaction employs readily available N3SO2CF3 as a bifunctional reagent to concurrently incorporate both CF3 and N3 groups, which avoids the use of their expensive and low atom economic precursors. A wide range of functional groups, including bio-relevant heterocycles and amino acids, were tolerated. Application of this method was further demonstrated by scale-up synthesis (5 mmol), product derivatization to CF3-containing medicinal chemistry motifs, as well as late-stage modification of natural product and drug derivatives.

FeCl2-Mediated Regioselective Aminochlorination and Aminoazidation of Styrenes with Trifluoromethanesulfonyl Azide.

An efficient aminochlorination reaction of stryenes is described using N3SO2CF3 as an amination reagent and FeCl2 as a chloride source. The operationally simple procedure features mild reaction conditions, good functional group compatibility, and high regioselectivity. An example of aminobromination using FeBr2 is also realized. Additionally, a one-pot aminoazidation of styrenes is achieved by adding sodium azide to the reaction. The gram-scale synthesis and downstream derivatization of the products are showcased as well.

Development of morin-conjugated Au nanoparticles: exploring the interaction efficiency with BSA using spectroscopic methods.

In order to enhance its interaction efficiency with biomacromolecules for the usage as a therapeutic agent, we have conjugated morin, an antioxidant activity and anti-tumor drug, with citrate-coated Au nanoparticles (M-C-AuNPs). M-C-AuNPs were prepared by reducing chloroauric acid using trisodium citrate in the boiling condition, and the resulted M-C-AuNPs were characterized by UV-vis absorption spectroscopy, Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. In this article, UV-vis absorption spectroscopy in combination with fluorescence spectroscopy, and circular dichroism (CD) spectroscopy were employed to investigate the interactions between M-C-AuNPs and bovine serum albumin (BSA), C-AuNPs and BSA in a phosphate buffer at pH 7.4. By comparing the quenching constant KSV, effective quenching constant Ka, binding constant Kb and the number of binding sites n, it is clearly suggested that M-C-AuNPs could enhance the binding force of morin with BSA, which would pave the way for the design of nanotherapeutic agents with improved functionality.