Nature synthesis最新文献

Colloidal semiconductor nanocrystals based on CdSe have been precisely optimized for photonic applications in the visible spectrum, with modern products exhibiting structural uniformity, near 100% quantum yield and linewidths narrower than 100 meV. Here we report homogeneous nanocrystals with tunable bandgaps in the infrared spectrum based on HgSe and Hg_xCd_1−xSe alloys deriving from CdSe precursors. We find that Ag⁺ catalyses cation interdiffusion to reduce the CdSe–HgSe alloying temperature from 250 °C to 80 °C. Together with ligands that modulate surface cation exchange rates, interdiffusion-enhanced Hg²⁺ exchange of diverse CdSe nanocrystals proceeds homogeneously and completely. The products retain the size, shape and uniformity of the parent nanocrystals but exhibit enhanced absorption. After passivation with heteroepitaxial CdZnS shells, photoluminescence wavelengths are tunable in the shortwave infrared by composition without changing size, with 80–91% quantum yield and linewidths near 100 meV. These materials may find applications in infrared photonic devices and infrared bioimaging.

Macrolactones are privileged motifs in materials science, aromachemicals and pharmaceuticals. The pivotal ester linkage is often formed from chiral secondary alcohols, with macrolactonization using stoichiometric reagents to ensure retention or inversion of stereochemistry without compromising enantiopurity. An ideal strategy for macrolactonization is via dynamic kinetic resolution (DKR), which involves the simultaneous formation of the ester bond and introduction of a chiral centre with high stereocontrol. Surprisingly, a DKR method within the context of macrocyclization is yet to be reported. Here, using a chemoenzymatic approach, the macrocyclic DKR of seco esters affords enantioenriched macrolactones. An optimized protocol (using Candida antarctica lipase B (~0.04 mol%) and Shvo’s catalyst) forms 14–19-membered macrocycles with excellent enantioselectivities (85–99% e.e.). A variety of macrolactones were synthesized including aliphatic macrocycles, meta- and paracyclophanes as well as a macrodiolide via a dimerization protocol that was converted to the natural product macrolide (−)-pyrenophorin.

Efficient methods for achieving desaturation of carbonyl compounds are highly sought after in organic chemistry. In contrast to synthetic approaches, enzymatic desaturation systems offer the potential to enhance sustainability and selectivity but have remained elusive. Here we report the development of an enzymatic desaturation system based on flavin-dependent ene-reductases for desymmetrizing cyclohexanones. This platform facilitates the synthesis of a wide array of chiral cyclohexenones bearing quaternary stereocentres—structural motifs commonly present in bioactive molecules—with excellent yields and enantioselectivities. Experimental and computational mechanistic studies reveal the roles of key active-site residues that enable the formation and stabilization of an enolate intermediate in the desaturation event. Additionally, by leveraging these insights, we have devised a biocatalytic strategy for the synthesis of enones by reductively desymmetrizing cyclohexadienones. This method yields the opposite enantiomer compared to our desaturation system, underscoring the enantiodivergence and broad applicability of our flavin-based desymmetrization approaches.

Traditional metal-catalysed cross-couplings of alkyl halides for C(sp³)–C(sp²) bond formation are often challenging to achieve. Processes where the alkyl halide is initially converted into a radical species can provide valuable complementarity. So far, these strategies are almost exclusively orchestrated by silicon-based reagents, which can be expensive, have low atom economy and are sensitive to steric factors. Here we report the use of the stable Lewis acid–Lewis base complex Me₃N–BH₃, which, upon conversion into its corresponding amine-ligated boryl radical, enables nickel- and copper-catalysed cross-coupling of alkyl iodides and bromides with electrophilic aryl bromides and nucleophilic aryl boronic acids. Mechanistically, this method uses the amine borane radical’s propensity to activate halides via halogen-atom transfer through highly polarized transition states. This reactivity features mild conditions and broad tolerability of functional groups and engages sterically hindered alkyl halides.

The synthesis of nitrogen-containing polycyclic aromatic heterocycles (PAHs) is important because of their expanding range of applications. Over the past decade, the preparation of PAHs has largely relied on complex, multistep processes. These methods necessitate the use of expensive transition-metal catalysts and sophisticated techniques. Here we report a one-pot, metal-free synthesis of PAHs that addresses the limits of traditional methods. Our method uses a sequence of imine condensation, nucleophilic aromatic substitution and intramolecular Friedel–Crafts reactions, leading to the synthesis of aromatic and seven-ring fused 5,11,17-triazatrinaphthylene compounds. The approach can incorporate various substituents, including alkyl chains and heteroatoms, with high regioselectivity and efficiency. In addition, this method enables the in situ crystallization of 5,11,17-triazatrinaphthylene molecules using precipitation under high pressure, potentially removing the need for chromatographic separation and allowing for bulk-scale production. This process is particularly beneficial for creating crystalline, porous polyaromatic heterocyclic materials with tunable permanent porosity.