Novel tridentate diamino organomanganese(II) complexes as homogeneous catalysts in manganese(II)/copper(I) catalyzed carbon–carbon bond forming reactions

Abstract

The new, paramagnetic arylmanganese (II) (3a), n-Bu (3b)). Complex 2, using CuCl as a co-catalyst, is an effective catalyst system for cross-coupling of Grignard reagents with alkyl bromides and the 1,4-addition of organomagnesium halides to h,i-unsaturated ketones. No further additives or co-solvents are necessary. For both reactions a dramatic decrease in reaction times is observed when compared to standard manganese/copper systems. Alkyl bromides with unsaturated or heteroatom functionalities can be cross-coupled. Also, excellent reactivity towards normally unreactive i,i-disubstituted ketones has been observed in the 1,4-addition reaction.

Chiral platinum and palladium complexes containing functionalized C2-symmetric bisaminoaryl ‘Pincer’ ligands

“…Dependent on the choice of the metal M and the donor E, various reactions were catalyzed, such as hydrogenation [5], alkane dehydrogenation [6], C C bond formation [7][8][9][10][11][12][13], C C bond cleavage [14], and polymerization [15]. Early approaches towards asymmetric catalysis involved the replacement of the NMe 2 groups in the NCN pincer ligand by asymmetrically substituted pyrrolidines (A in Chart 1) [16].…”

Catalysts for Cross‐Coupling Reactions with Non‐activated Alkyl Halides

“…a-Branched alkyl bromides, which are not suitable substrates for purely manganese- [12] or copper-catalyzed [13] reactions, can be coupled by applying the Mn/Cu protocol. [14] Cahiez et al reported an improved copper-catalyzed Kumada protocol with alkyl halides in 2000 (Scheme 3). In the presence of Li 2 CuCl 4 (3 mol %), functionalized alkyl bromides react in good yields at room temperature.…”

Transition Metal-Catalyzed Activation of Aliphatic C−X Bonds in Carbon−Carbon Bond Formation

“…17 The manganese complex 8 with a nontransferable ligand which can be prepared in situ has been shown to be a powerful catalyst in the cross-coupling reaction of alkyl bromides with various Grignard reagents in the presence of CuCl as a cocatalyst (Table 2). 18,19 It is highly chemoselective, and functional groups such as ketone and ester remain intact under the reaction conditions. Reaction of an R-bromoketal 9 with vinylmagnesium bromide in the presence of a catalytic amount of FeCl 3 affords the corresponding cross-coupling product 10 (eq 4).…”