ABSTRACT
The enantioselective silver-catalyzed propargylation of N-sulfonylketimines is described. This reaction proceeds in high yield and excellent enantiomeric ratio and is compatible with a wide variety of diaryl- and alkylketimines. Synthetic transformations of homopropargylic products via enyne ring-closing metathesis, Sonogashira cross-coupling, and reduction reactions proceed with high stereochemical fidelity. Both allenyl and propargyl borolane reagents can be used to obtain homopropargylic products, a distribution most consistent with a mechanism involving transmetalation of the silver catalyst with the borolane reagent.
Subject(s)
Imines/chemistry , Nitriles/chemistry , Silver/chemistry , Sulfones/chemistry , Boron Compounds/chemistry , Catalysis , Molecular Structure , Pargyline/chemistry , StereoisomerismABSTRACT
The stereospecific ring-opening of O-heterocycles to provide acyclic alcohols and carboxylic acids with controlled formation of a new C-C bond is reported. These reactions provide new methods for synthesis of acyclic polyketide analogs with complex stereochemical arrays. Stereoselective synthesis of the cyclic template is utilized to control relative configuration; subsequent stereospecific nickel-catalyzed ring-opening affords the acyclic product. Aryl-substituted tetrahydrofurans and tetrahydropyrans undergo nickel-catalyzed Kumada-type coupling with a range of Grignard reagents to furnish acyclic alcohols with high diastereoselectivity. Enantioenriched lactones undergo Negishi-type cross-coupling with dimethylzinc to afford enantioenriched carboxylic acids. Application in a two-step enantioselective synthesis of an anti-dyslipidemia agent is demonstrated.
Subject(s)
Furans/chemistry , Lactones/chemistry , Pyrans/chemistry , Carboxylic Acids/chemistry , Catalysis , Stereoisomerism , Substrate SpecificityABSTRACT
A mild protocol for the synthesis of diaryl and heteroaryl sulfides is described. In a one-pot procedure, thiols are converted to sulfenyl chlorides and reacted with arylzinc reagents. This method tolerates functional groups including aryl fluorides and chlorides, ketones, as well as N-heterocycles including pyrimidines, imidazoles, tetrazoles, and oxadiazoles. Two compounds synthesized by this method exhibited selective activity against the MCF-7 breast cancer cell line in the micromolar range.
Subject(s)
Antineoplastic Agents/chemical synthesis , Chlorides/chemistry , Imidazoles/chemistry , Ketones/chemistry , MCF-7 Cells/chemistry , MCF-7 Cells/drug effects , Sulfenic Acids/chemical synthesis , Sulfhydryl Compounds/chemistry , Sulfides/chemical synthesis , Antineoplastic Agents/chemistry , Catalysis , Humans , Molecular Structure , Sulfides/chemistryABSTRACT
Alkyl Grignard reagents that contain ß-hydrogen atoms were used in a stereospecific nickel-catalyzed cross-coupling reaction to form C(sp(3))-C(sp(3)) bonds. Aryl Grignard reagents were also utilized to synthesize 1,1-diarylalkanes. Several compounds synthesized by this method exhibited selective inhibition of proliferation of MCF-7 breast cancer cells.
