Carbon-Hydrogen and C-X (X=Cl or SiMe3) Bond Activation. 1-Cyclopalladation and Oxidation of Some Derivatives of 2-naphthalene

Article abstract of DOI:10.1039/DT9940002293

The regioselective palladation reactions of 3-substituted derivatives of 2-<(dimethylamino)methyl>naphthalene, C10H6(CH2NMe2)-2-R-3 (R=Cl, SiMe3 or OSiMe3), were studied.For the substrate with R=Cl, no cyclopalladation at position 1 was observed and the co-ordination complex was isolated.The 3-palladated product was formed in 10percent yield via C-Cl activation.The reaction of 2-<(dimethylamino)methyl>-3-methylnaphthalene with Pd(O2CMe)2 and work-up with LiCl did lead to palladation at position 1, the resulting complex being isolated in 96percent yield.The crystal structure of bis(acetonitrile) <2-<(dimethylamino)methyl>-3-methyl-1-naphthyl>palladium trifluoromethanesulfonate was solved.Monoclinic, space group P2₁/n, with a=13.193(1), b=11.801(1), c=14.797(1) Angstroem, β=105.15(1) deg, Z=4.The structure was refined to R=0.042 for 3455 reflections with I > 2.5?(I).Palladation at position 1 was also achieved by oxidative addition of 1-bromo-2-<(dimethylamino)methyl>naphthalene to (dba=dibenzylideneacetone).Protection of C(3) with R=SiMe3 resulted in quantitative replacement of the SiMe3 group by palladium.Silicon-oxygen bond cleavage was observed when the substrate with R=OSiMe3 was treated with Pd(O2CMe)2.Palladium bis<3-<(dimethylamino)methyl>-2-naphtholate> was obtained quantitatively.Oxidation of several arylpalladium complexes with tBuO2H was achieved in the presence of (acac=acetylacetonate) or <2> (cod=cycloocta-1,5-diene) as catalyst.The corresponding 1-naphthols were prepared in yields varying from 33 to 78 percent.In a number of cases the corresponding 1,4-naphthoquinones were prepared in yields varying from 18 to 38percent.

Full text of DOI:10.1039/DT9940002293

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