Catalytic Hydrogenation of Alkenes Using Zirconocene–Alkene Complexes

Abstract

Hydrogenation reactions of alkenes were catalyzed by zirconium–alkene complex derivatives which were prepared from Cp2ZrCl2 (Cp = η5-C5H5) and n equiv. of RR′CHCH2M (M = MgX or Li). By the use of three or more equiv. of EtMgBr relative to Cp2ZrCl2, the product yield of hydrogenation of 1-decene was remarkably improved most likely due to the stabilization of the Zr(II) species.

Transition metal catalyzed carbon‐silicon bond forming reactions using chlorosilanes promoted by Grignard reagents

“…Scheme shows a possible pathway for this reaction. Zirconate complex 7 ,15 formed by the reaction of zirconocene–alkene complex 6 with n BuMgCl, directly reacts with chlorosilanes at a terminal olefinic carbon to form dialkylzirconocene complex 8 . The resulting dialkyl zirconocene complex 8 undergoes β‐hydrogen elimination with removal of H a or H b to afford alkenylsilane or allylsilane, respectively 16.…”

Highly regio- and diastereo-selective carbon–carbon bond formation reaction of unsymmetrical zirconacyclopentanes using copper salt

“…Recently we reported the unprecedented highly regioselective transmetalation of zirconacyclopentanes such as 1a with EtMgBr to afford Grignard compound 2a. 1 It is known that zirconacyclopentane 1a is prepared by the reaction of (C 5 H 5 ) 2 Zr(CH 2 NCH 2 ), 2 which is generated from (C 5 H 5 ) 2 ZrCl 2 , 2 equiv. of EtMgBr and b-methylstyrene with high stereo-and regio-selectivity.…”

Completion of a catalytic cycle of zirconium-catalyzed alkylation of silanes by addition of organic halides

“…We have found and reported catalytic cycles containing a Zr(II) species and zirconacycles in carbon-carbon bond formation by the reaction of olefins and/or acetylenes with Grignard reagents. [1][2][3][4][5] One principle of the Zr(II)-mediated or -catalyzed reactions is the use of facile interchange of its oxidation states, II and IV. The zirconium(II) species is known to be of good pelectron accepting ability and oxidatively couples two unsaturated organic molecules.…”

“…During the coupling reaction, the Zr(II) species is converted into Zr(IV). On these bases, zirconium(II)-catalyzed reactions have been developed involving olefins [1][2][3][4] and, in some cases, acetylenes. 5 We also reported not only unsaturated substrates but also dihydrogen 2 or silanes 3 as partners of unsaturated compounds such as olefins.…”

“…6 It is interesting that (1) H 2 SiPh 2 does not react at all with the more sterically hindered Pr i MgBr under the same conditions [eqn. (2)].…”