Synthesis of Forms of a Chiral Ruthenium Complex Containing a Ru–C_olefin(sp²) Bond and Their Application to Catalytic Asymmetric Cyclopropanation Reactions

Abstract

Organometallic complexes [Ru–Colefin(sp2)–Ru­(II)–Pheox 2a–2d] containing a Ru–Colefin(sp2) bond have been prepared from unsaturated chiral oxazoline derivatives and evaluated for asymmetric cyclopropanation reactions. The corresponding optically active cyclopropanes were obtained with high yields and high stereoselectivities (≥99/<1 trans/cis, 99% trans ee). The enantioselectivities were found to be affected by the geminal substituent on the Ru–C­(sp2) bond. In particular, Ru­(II)–Prox catalyst 2c, in which there was no geminal substituent on the metal, was shown to have the highest enantioselectivities.

Sustainable Hydrogenation of Vinyl Derivatives Using Pd/C Catalysts

“…The nucleophilic addition proceeds under superbasic conditions in good yields without the use of gaseous acetylene and can be safely carried out in a laboratory. Labeled compounds with deuterium [21] and carbon 13 C [22] incorporation can also be obtained that increase applications in further transformations: polymerization [23], Heck-like reactions [24], cycloaddition [25,26], and many others. Here, we expand the scope of applications of vinyl derivatives and demonstrate that molecular hydrogen can be successfully added to functionalized vinyl derivatives.…”

Ru(II)‐Pheox Catalyzed Highly Stereoselective Cyclopropanation of Allyl‐ and Vinylsilanes with Diazoesters and Their Synthetic Applications

“…Previously, we had developed Ru(II)‐Pheox as a highly effective catalyst in asymmetric cyclopropanations [9] . Furthermore, we recently expanded our capability for asymmetric cyclopropanation by the addition of Ru(II)‐Prox as an efficient catalyst for this process [10] …”

“…[9] Furthermore, we recently expanded our capability for asymmetric cyclopropanation by the addition of Ru(II)-Prox as an efficient catalyst for this process. [10] Herein, we report the stereoselective cyclopropanation of diazoesters with various allylsilanes and vinylsilanes in the presence of Ru(II)-Pheox and Ru(II)-Prox catalysts, and its synthetic applications (Scheme 1e). In order to establish the reactivity and stereoselectivity of the proposed reaction, initially, allytrimethylsilane 1 was reacted with 0.2 mmol scale of various diazoesters 2 in the presence of 1 mol% of cat.…”

Catalysis with cycloruthenated complexes

“…In 2020, a related series of cationic ruthenium complexes containing Ru–C(sp 2 )–olefin bonds were synthesised through C–H activation of alkenyl oxazoline ligands and applied to enantioselective cyclopropanation ( Scheme 53 ). 89 Of the newly synthesised complexes (Ru89–Ru92), Ru91 possessed superior reactivity to the standard phenyl-substituted catalyst. The absence of a geminal substituent was found to afford the best enantioselectivities for a range of trans -allylic diazoacetates in this transformation.…”