Phenyl-metal compounds

Recently, the following two chiral reactions of phenyl alkyl ketone were reported on hydrogenations in the presence of bis(oxazolinyl)phenyl metal compounds (8.45, 8.46), as shown in Eqs. (8.10) [40,41] and (8.11) [42]. For the latter bis(oxazolinyl) phenyl ruthenium catalyst (8.46), Nishiyama reported, furthermore, on the significant enhancement of enantioselectivity with a zinc chloride-bridged ruthenium compound [42]. 

Phenyl Derivatives Table VII). Very few phenyl metal compounds have... 

The material reviewed in this Chapter hitherto has focused on metallacarboranes in which the metal atom is a vertex in an icosahedral cage framework. Until recently, monocarbollide metal compounds with core structures other than 12 vertexes were very rare since suitable carborane precursors were not readily available." However, Brellochs recent development of the reaction of decaborane with aldehydes to give 10-vertex monocarboranes permits a considerable expansion in this area of boron cluster chemistry. As a consequence, several intermediate-sized monocarboranes are now easily accessible and we have recently begun to exploit the opportunities that these present. In particular, we have focused thus far on complexes derived from the C-phenyl-substituted species [6-Ph- zJo-6-CBgHii] It is clear from these initial studies that a wealth of new chemistry remains to be discovered in this area, not only from among the metal derivatives of PhCBg car-boranes such as those discussed in this section, but also in the metal complexes of other newly available carboranes. 

Unusual ortho metallation of one or two phenyl groups of C(PPh3)2 is observed by reacting with some second and third row group 9 and 10 transition metal compounds. As mentioned before, transition metal precursors were compounds with either vacant coordination sites or easily removable ligands. Doubly ortho metalated compounds can also be seen as pincer carbodiphosphoranes. 

A few other miscellaneous reactions may be noted. Vinylsilicon-metal compounds in entries 4 and 30 undergo addition of HBr in an anti-Markownikoff sense to give 2-bromoethyl derivatives in some other related systems, HBr induces cleavage (see Section III,B,2). Also, the phenyl group in a phenyl-silicon-metal compound can undergo hexahapto interaction with a Cr(CO)3 group (entry 39). 

The out-of-plane terms (Eq. 3.33) are used for sp2 hybridized and aromatic systems such as carboxylates and phenyl groups. In metal compounds, out-of-plane terms are sometimes used for the modeling of square planar complexes (see Fig. 3.15, Section 3.6 below). 

Deuterium labelling combined with deuterium decoupling is well known as a method in spectral analysis and in stereochemical and conformational studies. The deuterium-decoupled proton spectra of XCHD.CHDY compounds produced during mechanistic studies are useful for determining the stereochemical course of reactions such as the methoxymercuration of ethylene, (478) the conversion of tyramine into tyrosol, (479) the non-catalytic addition of deuterium molecules to cyclopentadiene, (480) and alkyl transfer and olefin elimination in 2-phenyl-l,2-dideuterioethyl transition metal compounds. (481) The proton spectra of [ H ]- and [ Hg]-t-butylcyclohexanes were... 

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