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Direct C-H bond activation in the (S a )-BINOL-derived phosphite (HL) afforded the dimeric cyclopalladated complex (S a ,S a )-{Pd(η 2 -L)(µ-Cl)} 2 (1), which is the first optically active phosphapalladacycle bearing a phosphorus atom in an axially chiral environment. The ortho-palladated structure of complex 1 was confirmed by spectral ( 1 H and 31 P) investigations of mononuclear derivatives and the X-ray diffraction study of the phosphane adduct (η 2 -L)PdCl(PPh 3 ) (3). The enantiomeric purity of the starting ligand remained unchanged in the PC-palladacycle under the thermal conditions used for the cyclopalladation (∼110 °C); this fact was confirmed by the 31 P NMR spectroscopy after chiral derivatization of dimer (S a ,S a )-1 with the (R C )-valinate auxiliary ligand. The trans(N,C)configuration of the valinate complex (4) was supported by DFT calculations. The chirality transfer in the new system was discussed on the basis of X-ray diffraction data for the phosphane adduct rac-3 and DFT calculations performed for both mononuclear derivatives.

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High catalytic activity of N,N dimethylaminomethylferrocene cyclopalladated derivative was demonstrated in the the Suzuki-Miyaura cross coupling of aryl bromides with phenyl boronic acid, which allowed us to carry out the reaction under extremely mild conditions. In the last decades, cyclopalladated complexes (CPC), possessing high thermal, oxidative, and hydrolytic stabili ty, showed themselves as excellent highly efficient cata lysts of the cross coupling reactions. 1,2 Starting our pro gram for the testing chiral CPC in enantioselective cataly sis, we have chosen the Suzuki-Miyaura reaction for the following reasons: 1) with the general practice of thermal (60-160 °C) 1,3,4 activation of this type cross coupling processes, only several precedents of carrying out such reactions at room temperature are known; 5,6 2) the only example of moderately successful (up to 49% ee) enantiose lective catalysis of cross coupling with palladacycles deals with exactly the Suzuki-Miyaura reaction. 7In our search for the complex capable to catalyze reac tions of this type under mild conditions, we have chosen the known 8 CN palladacycle based on N,N dimethylami nomethylferrocene (1), since the ferrocenyl CPC with other N donor groups have proved especially efficient cat alysts of achiral Suzuki-Miyaura reactions. 5,6 As far as we know, only one short communication has been pub lished on the application of this CPC in catalysis: the Heck reaction in the high temperature regime (140-160 °C) and only involving active aryl iodides. 9The present work deals with evaluation of catalytic activity of racemic dimer 1 (rac 1) in the achiral Suzu ki-Miyaura reaction and a possibility to carry out it un der the maximum mild conditions necessary for the fur ther accomplishment of asymmetric versions of this pro cess. Preliminary results of this study have been reported earlier. 10 Results and DiscussionWe used a cross coupling of phenylboronic acid with para tolyl bromide (2) as a model version of the Suzu ki-Miyaura reaction. The presence of the Me group in the starting substrate simplified monitoring the reaction progress by 1 H NMR. In addition, a reduced reactivity of aryl halides with electron donating substituents 1 in the cross coupling processes provides higher correctness of such model reaction as a method for the evaluation of a catalyst efficiency.On catalysis with dimer rac 1, in the reaction of aryl bromide 2 with phenylboronic acid, carried out at room temperature in air (Scheme 1), the target biaryl 3a is formed in high yield (94%, Table 1, entry 1) at moderate loading* of the catalyst in 2.5 mol.%.Unfortunately, the attempts to decrease amount of the catalyst have proved not very successful: when the con centration of dimer rac 1 was decreased to 0.05 mol.%, the final product 3a in the same temperature regime is formed only in insignificant yield (7%, entry 2). The yield is somewhat increased only on heating (20%, entry 3).A possibility to carry out the model Suzuki-Miyaura reaction even at negative temperature (-18 °C) upon ...