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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]

Herein, the first palladium-catalyzed intramolecular enantioselective C(sp 3 )-H insertion reaction of donor-donor carbenes has been successfully achieved. This facile protocol enables the rapid construction of a collection of enantioenriched decorated indolines with two contiguous stereocenters in a single step. Both enynones and diazo compounds are efficient donor-donor carbene precursors for this reaction. By an adjustment of ligands and protecting groups of the substrates, the palladium-carbene intermediates from diazo compounds afford sparse trans -indolines with excellent enantioselectivities, while carbenes from enynones deliver cis -indolines exclusively. Based on the control reactions and Hammett analysis, a stepwise Mannich-type pathway through a short-lived and compact zwitterionic intermediate is proposed., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)