(Arene)transition metal complexes in organic synthesis

Treatment of (1,4-dimethyltetrahydroquinoline)RuCp+ with NaH in THF followed by addition of electrophiles results in formation of benzylic quaternary carbon centers. Both exo and endo benzylic hydrogens were activated toward deprotonation by the RuCp + unit, and alkylations proceeded with complete stereocontrol. Similar results were obtained for the alkylation of (1,3-dimethylindoline)RuCp + complex. After functionalization of the arene ligand, the metal moiety can be released under mild conditions and can be recovered in a reusable form.; Stabilized secondary enolates attached to (arene)RuCp+ complexes via an amide linkage were found to participate in nucleophilic aromatic addition reactions. Further deprotonation of the intermediates followed by O-alkylation resulted in the formation of novel cyclohexadienyl-Ru azaspirocycles. A number of reaction conditions were screened to optimize the reaction. Optimum conditions were found for the reagent combination of K2CO3/DMSO/KOtBu/18-crown-6/electrophile. Under these conditions, enolate additions proceeded with complete stereoselectivity and oxygen alkylations gave only the E-stereoisomer. The reactions proceeded with good yields with little influence by substitution on the aromatic ring. Electrophiles such as methyltosylate, dimethylsulfate, acetic anhydride and allyl tosylate were effective oxygen alkylating agents.; In contrast, stabilized enolates attached to (arene)RuCp+ complexes via an ethylene linkage were found to participate in nucleophilic aromatic substitution reactions resulting in the formation of substituted 2-tetralones. The reagent combination of NaH/2,6-di- tertiary-butylphenol/DMSO was effective for this transformation. Direct benzylic manipulation of the product was found to be difficult. Attempts to construct benzylic quaternary carbon centers directly by using tertiary stabilized enolates resulted in deacetylation products. These products were easily functionalized at the benzylic position to create benzylic quaternary carbon centers. Removal and recovery of the metal center were also demonstrated.; (Indole)Cr(CO)3 complexes substituted at the C-2 and/or C-3 positions were reduced to the corresponding indoline complexes by a hydride donor in trifluoroacetic acid. NaBH3CN and NaBH4 are superior to Et3SiH as hydride sources. Reductions using NaBH 3CN proceeded with greater stereoselectivity than reductions using NaBH 4. With certain (indole)chromium complexes, this stereoselectivity is a result of preferential hydride addition from the endo face of the aromatic ring.; In summary, four significant results were obtained in the research area of (arene)transition metal complexes in organic synthesis. The methods developed in the course of this research are expected to be useful in the synthesis of a number of structurally elaborate and/or biologically active natural and unnatural products.