No abstract

A catalytic system for titanocene-catalyzed epoxide hydrosilylation is described. It features a straightforward preparation of titanocene hydrides that leads to a reaction with low catalyst loading, high yields, and high selectivity of radical reduction. The mechanism was studied by a suite of methods, including kinetic studies, EPR spectroscopy, and computational methods. An unusual resting state leads to the observation of an inverse rate order with respect to the epoxide.

We describe atitanocene(III)-catalyzed deuterosilylation of epoxides that provides b-deuterated anti-Markovnikovalcohols with excellent D-incorporation, in high yield, and often excellent diastereoselectivity after desilylation. The key to the success of the reaction is an ovel activation method of Cp 2 TiCl 2 and (tBuC 5 H 4 ) 2 TiCl 2 with BnMgBr and PhSiD 3 to provide[(RC 5 H 4 ) 2 Ti(III)D] without isotope scrambling.Itwas developed after discovering an off-cycle scrambling with the previously described method. Our precision deuteration can be applied to the synthesis of drug precursors and highlights the power of combining radical chemistry with organometallic catalysis.

Die einfacheE rzeugung von Titanocen(III)-Hydriden ermçglicht Epoxid-Hydrosilylierungen mit geringen Katalysatormengen, hohen Ausbeuten und Selektivitäten in der Radikalreduktion. Die Untersuchung des Mechanismus mittels kinetischer,E PR-spektroskopischer und theoretischer Methoden legt einen ungewçhnlichen Ruhezustand des Katalysators nahe,d er zu einer inversen Reaktionsordnung im Epoxid führt.

We describe a titanocene(III)‐catalyzed deuterosilylation of epoxides that provides β‐deuterated anti‐Markovnikov alcohols with excellent D‐incorporation, in high yield, and often excellent diastereoselectivity after desilylation. The key to the success of the reaction is a novel activation method of Cp2TiCl2 and (tBuC5H4)2TiCl2 with BnMgBr and PhSiD3 to provide [(RC5H4)2Ti(III)D] without isotope scrambling. It was developed after discovering an off‐cycle scrambling with the previously described method. Our precision deuteration can be applied to the synthesis of drug precursors and highlights the power of combining radical chemistry with organometallic catalysis.