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Described herein is a dirhodium(II)‐catalyzed silylation of propargyl esters with hydrosilanes, using tertiary amines as axial ligands. By adopting this strategy, a range of versatile and useful allenylsilanes can be achieved with good yields. This reaction not only represents a SN2′‐type silylation of the propargyl derivatives bearing a terminal alkyne moiety to synthesize allenylsilanes from simple hydrosilanes, but also represents a new application of dirhodium(II) complexes in catalytic transformation of carbon‐carbon triple bond. The highly functionalized allenylsilanes that are produced can be transformed into a series of synthetically useful organic molecules. In this reaction, an intriguing ON‐OFF effect of the amine ligand was observed. The reaction almost did not occur (OFF) without addition of Lewis base amine ligand. However, the reaction took place smoothly (ON) after addition of only catalytic amount of amine ligand. Detailed mechanistic studies and density functional theory (DFT) calculations indicate that the reactivity can be delicately improved by the use of tertiary amine. The fine‐tuning effect of the tertiary amine is crucial in the formation of the Rh−Si species via a concerted metalation deprotonation (CMD) mechanism and facilitating β‐oxygen elimination. [ABSTRACT FROM AUTHOR]

The rapid synthesis of crystalline covalent triazine frameworks (CTFs) and exploration of the polymerization mechanism are highly desired for the research of crystalline porous polymers, but have not yet been reported. Herein, we demonstrate a scalable microwave‐assisted synthetic strategy to successfully prepare a series of highly crystalline and semiconducting CTFs within 20 minutes for the first time. By in situ imaging and time‐dependent characterization, we proposed an ordered two‐dimensional (2D) polymerization mechanism for crystalline CTFs, in which the monomers rapidly polymerize into periodic 2D molecular sheets within 10 s and then grow into more ordered framework structures. Photocatalytic study of CTF with different crystallinity revealed that large crystalline domain could significantly improve the photocatalytic performance. Single‐layer and few‐layer crystalline 2D triazine polymer nanosheets could be obtained through simple ball‐milling exfoliation of the bulk layered CTFs and exhibit nearly fivefold improved photocatalytic hydrogen evolution rate up to 7971 μmol g−1 h−1. [ABSTRACT FROM AUTHOR]

Rücktitelbild: Rapid, Ordered Polymerization of Crystalline Semiconducting Covalent Triazine Frameworks (Angew. 2D ordered polymerization, 2D polymers, covalent triazine frameworks, large-scale synthesis, photocatalysis Keywords: 2D ordered polymerization; 2D polymers; covalent triazine frameworks; large-scale synthesis; photocatalysis EN 2D ordered polymerization 2D polymers covalent triazine frameworks large-scale synthesis photocatalysis 1 1 1 01/18/22 20220121 NES 220121 B Die schnelle Synthese b von kristallinen halbleitenden kovalenten Triazin-Gerüststrukturen (CTFs) durch einen zweidimensionalen geordneten Polymerisationsmechanismus wird von Yuxi Xu et al. in ihrer Zuschrift demonstriert (e202113926). [Extracted from the article]