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We report an iridium-catalysed stereoselective cyclisation of aryl alkynes with tethered esters and imides to give silyl-protectedO,O- andN,O-acetals. 

Abstract Enantioenriched propargylic and allenic derivatives of silicon, germanium, and tin are versatile building blocks for stereoselective synthesis. Consequently, considerable efforts toward their efficient and selective synthesis have been made, both through classical approaches for chirality transfer and catalytic enantioselective strategies that employ the latest developments in transition metal catalysis, organocatalysis, and photoredox catalysis. In this review, we survey broadly applicable synthetic strategies and discuss the scope and mechanistic details for specific protocols that afford these compounds in a regio‐ and stereoselective manner. 

Abstract By utilizing bicontinuous and nanoporous ordered nanonetworks, such as double gyroid (DG) and double diamond (DD), metamaterials with exceptional optical and mechanical properties can be fabricated through the templating synthesis of functional materials. However, the volume fraction range of DG in block copolymers is significantly narrow, making it unable to vary its porosity and surface‐to‐volume ratio. Here, the theoretically limited structural volume of the DG phase in coil‐coil copolymers is overcome by enlarging the conformational asymmetry through the association of mesogens, providing fast access to achieving flexible structured materials of ultra‐high porosities. The new materials design, dual‐extractable nanocomposite, is created by incorporating a photodegradable block with a solvent‐extractable mesogen (m) into an accepting block, resulting in a new hollow gyroid (HG) with the largely increased surface‐to‐volume ratio and porosity of 77 vol%. The lightweight HG exhibits a low refractive index of 1.11 and a very high specific reduced modulus, almost two times that of the typical negative gyroid (porosity≈53%) and three times that of the positive gyroid (porosity≈24%). This novel concept can significantly extend the DG phase window of block copolymers and the corresponding surface‐to‐volume ratio, being applicable for nanotemplate‐synthesized nanomaterials with a great gain of mechanical, catalytic, and optoelectronic properties. 

Abstract Propargylic ethers serve as useful intermediates for the synthesis of a variety of complex targets. However, propargylic substitution of prefunctionalized alkyne starting materials remains the dominant method for the synthesis of propargyl ethers, while direct etherification of simple alkynes via propargylic C−H functionalization remains largely underreported. Herein, we report an organometallic umpolung approach for iron‐mediated C−H propargylic etherification. A telescopic protocol for iron‐mediated C−H deprotonation followed by mild oxidative coupling with alcohols enabled the use of simple or functionalized alkynes for the expedient synthesis of propargylic ethers with excellent functional group compatibility, chemoselectivity and regioselectivity. 

Abstract We report a highly enantioselective intermolecular C−H bond silylation catalyzed by a phosphoramidite‐ligated iridium catalyst. Under reagent‐controlled protocols, propargylsilanes resulting from C(sp³)−H functionalization, as well the regioisomeric and synthetically versatile allenylsilanes, could be obtained with excellent levels of enantioselectivity and good to excellent control of propargyl/allenyl selectivity. In the case of unsymmetrical dialkyl acetylenes, good to excellent selectivity for functionalization at the less‐hindered site was also observed. A variety of electrophilic silyl sources (R₃SiOTf and R₃SiNTf₂), either commercial or in situ‐generated, were used as the silylation reagents, and a broad range of simple and functionalized alkynes, including aryl alkyl acetylenes, dialkyl acetylenes, 1,3‐enynes, and drug derivatives were successfully employed as substrates. Detailed mechanistic experiments and DFT calculations suggest that an η³‐propargyl/allenyl Ir intermediate is generated upon π‐complexation‐assisted deprotonation and undergoes outer‐sphere attack by the electrophilic silylating reagent to give propargylic silanes, with the latter step identified as the enantiodetermining step.