RuCl, catalyst

An alternative oxidation using O2 and a RuCls catalyst converted pyridine to pyridine A-oxide. Bromamine-T and RuCls in aq. acetonitrile also oxidizes pyridine to the A-oxide. Tertiary amines are oxidized to the A-oxide with O2 and Fe203 in the presence of an aliphatic aldehyde. " Oxygen and a cobalt-Schiff base complex also oxidzes tertiary amines, including pyridine. ... 

In the same year, Doi and Tamura [19] reported RuCls catalysts for WGS reaction in alkaline medium. The activity results are presented in Table 7.8. The RUCI3-KOH catalyst system exhibited much higher activity than the Ru3(CO)i2-KOH system. An increase in the initial concentration of KOH resulted in the acceleration in the rate of H2 formation for the WGSR using RUCI3. However, higher initial concentrations of KOH over 1.0 M caused heterogeneity of the catalyst solution. 

Figure 1.15 NMR spectra of poly(anfi-7-methylnorbomene) (a) syndiotactic all-cis polymer prepared using the ReCl, catalyst (b) atactic all-trans polymer prepared using the RuCls catalyst. Reproduced by kind permission of Elsevier Science Publishers from [61]...

Yuhong Zhang demonstrated the regioselective arylation of 2-phenylpyridine with aryl iodides with 5 mol% of the same easily available RuCls catalyst with K2CO3 in NMP at 150°C for a shorter time of 6 h but in the presence of benzoyl peroxide additive or benzoic acid additive that may play the same profitable role as acetate [(Eq. 10)] [76]. 

Scheme 26.12 shows examples of the synthesis of pyrroles. Dieltiens et al. obtained pyrroles 43 by an RCM/oxidation sequence of diallyamines 42 in which Grubbs s second-generation catalyst 2 and chloranil (44) were used simultaneously [19]. At first, Dieltiens et al. used an RuCls catalyst system for the oxidation [19b]. However, there was a modification to use chloranil (44) because of the slow reaction rate of the RuCb catalyst system. 

Various aliphatic and aromatic secondary alcohols can be oxidized with peracetic acid in the presence of RuCls catalyst to give the corresponding ketones with high efficiency [63]. 

The allylic position of steroidal alkene can be oxidized with t-BuOOH in the presence of a RuCls catalyst [Eq. (72)] [108],... 

Formaldehyde also reacts with butadiene via the Prins reaction to produce pentenediols or their derivatives. This reaction is cataly2ed by a copper-containing catalyst in a carboxyUc acid solution (57) or RuCl (58). The addition of hydrogen also proceeds via 1,2- and 1,4-addition. 

Ruthenium complexes have also been reported as active species for enan-tioselective Diels-Alder reactions. Faller et al. prepared a catalyst by treatment of (-)-[( ] -cymene)RuCl(L)]SbF6 with AgSbFe resulting in the formation of a dication by chloride abstraction [95]. The ligand was (-l-)-IndaBOx 69 (Scheme 36) and the corresponding complex allowed the condensation of methacrolein with cyclopentadiene in 95% conversion and 91% ee. As another example, Davies [96] prepared the complex [Ru(Fl20)L ( i -mes)] [SbFe]2 (with 70 as L in Scheme 36), and tested its activity in the same reaction leading to the expected product with similar activity and lower enan-tioselectivity (70%). 

Fig. 1. P MAS NMR spectrum of (a)Ru-BrNAP/PTA/y-Al203, and (b)Ru-BINAP crt rlex In order to find the characteristics of the immobilized catalyst, asymmetric hydrogenation of the prochiral C=C bond was performed as a model reaction. Firstly, three different homogeneous Ru-BINAP complexes including [RuCl2((R)-BINAP)], [RuCl((R)-BINAP)(p-cymene)]Cl and [RuCl((R)-BINAP)(Benzene)]Cl were immobilized on the PTA-modified alumina. Reaction test of immobilized catalysts showed that [RuCl2((R)-BINAP)] was the most active and selective so all the experiment were done using this catalyst afterwards.

RuyAl20s and Ru/MgO may be due to the presence of chlorine originating from RuCls used for catalyst preparation. 

Madsen and co-workers have reported an important extension to the amine alkylation chemistry, in which oxidation takes place to give the amide product [13]. A ruthenium NHC complex is formed in situ by the reaction of [RuCl Ccod)] with a phosphine and an imidazolium salt in the presence of base. Rather than returning the borrowed hydrogen, the catalyst expels two equivalents of H. For example, alcohol 31 and benzylamine 27 undergo an oxidative coupling to give amide 32 in good isolated yield (Scheme 11.7). 

It is well known that the metathesis activity of Ru catalysts stems from coordinative unsaturation and the generally accepted active species in RCM is a 14 electron RuCl lCH XL) fragment, where L = PCyj or NHC... 

Another method for reductive dimerization has been developed in hy-drosilylation. NiCl2-SEt2 is an effective catalyst in silylative dimerization of aromatic aldehydes with a hydrosilane (Scheme 12) [40]. A catalytic thiolate-bridged diruthenium complex [Cp RuCl(/ 2-SPrI)2RuCp ][OTf] also induces the conversion to 1,2-diaryl-1,2-disiloxyethane [41]. A dinuclear (siloxyben-zyl)ruthenium complex is considered to be formed, and the homolytic Ru - C bond fission leads to the siloxybenzyl radicals, which couple to the coupling product 14. 

The isomerization of the double bonds conjugated with the ester moiety to enol ethers can be carried out using RuCl(H)(CO)(PPh3)3 as catalyst (Scheme 42).69... 

A large number of catalysts or catalyst precursors for the reaction in Eq. (1) have been identified (Table 17.1). Almost all of these are complexes of Rh and Ru, although there are a few, less active, examples of fr, Pd, Ni, Fe, Ti, and Mo. The most active catalysts are RhCl(TPPTS)3, Rh(hfacac)(dcpb) and RuCl(OAc) (PMe3)4, with little difference between them after rough correction of the turnover frequencies (TOF) for pressure and temperature differences [38]. Musashi and Sakaki [39] argue that the barrier to C02 insertion into M-H bonds increases in the order Rh(I) < Ru(II) < Rh(I II) because Rh(lll)-formate bonds are too weak and Ru(II)-H bonds are too strong compared to the case of Rh(I). 

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