ABSTRACT
A new Pd-catalyzed reaction for the coupling between perfluoroalkyl iodides (R(F)I) and simple aromatic substrates is described. The perfluoroalkylated arene products are obtained in good to excellent yields in the presence of a phosphine-ligated Pd catalyst and Cs(2)CO(3) as a base. The development, optimization, scope, and preliminary mechanistic studies of these transformations are reported.
Subject(s)
Hydrocarbons, Iodinated/chemistry , Hydrocarbons, Iodinated/chemical synthesis , Palladium/chemistry , Alkylation , Catalysis , Combinatorial Chemistry Techniques , Molecular Structure , Phosphines/chemistryABSTRACT
The catalytic enantioselective intramolecular ring-opening of oxetanes with alcohols is catalyzed by (salen)Co(III) complexes. Either a monomeric or oligomeric catalyst can be used successfully in this transformation, providing 3-substituted tetrahydrofurans in both high yield and enantioselectivity. This methodology extends the range of electrophiles that can be activated toward highly enantioselective addition reactions by (salen)metal catalysts to an important new class.
Subject(s)
Cobalt/chemistry , Ethers, Cyclic/chemistry , Furans/chemical synthesis , Organometallic Compounds/chemistry , Catalysis , Cations/chemistry , Ethylenediamines/chemistry , Furans/chemistry , StereoisomerismABSTRACT
A mild method for the synthesis of 2-deoxysugars from the coupling of glycals with a range of nucleophiles is described. The method employs 1 mol % of an air- and moisture-tolerant rhenium-oxo complex [ReOCl3(SMe2)(Ph3PO)] as a catalyst for the formation of O-, N-, and S-alpha-glycosides. The catalytic system tolerates a number of commonly employed protecting groups, including isopropylidene acetals, alkyl and silyl ethers, acetates, and benzoates. Furthermore, the high-oxidation-state complex selectively catalyzes the coupling with the glycal acceptor in preference to oxidation of the glycals, alcohols, and even thiols.
Subject(s)
Glycosides/chemical synthesis , Rhenium/chemistry , Catalysis , Oxidation-ReductionABSTRACT
Titanium tetrakis(amido) complexes catalyze the intramolecular hydroamination of alkynes and allenes more efficiently than Cp-based species. We report here that electron-withdrawing and sterically demanding bis(sulfonamido) ligands lead to enhanced catalytic activity. Zirconium analogues have also been prepared, and the tosyl-substituted complex 20 has been structurally characterized. As in the titanium series, bis(sulfonamido) zirconium catalysts are more efficient in the intramolecular hydroamination of allenes than bis(cyclopentadienyl) complex Cp(2)ZrMe(2) (23). Furthermore, these compounds transform 1,3-disubstituted aminoallenes with high stereoselectivity to the Z-allylamines and allow the hydroamination of a trisubstituted allene. Titanium bis(sulfonamido) imido complex 27 was synthesized. It converts aminoallene 10 to cylic imine 11 with a rate comparable to that of tetrakis(amide) 15, supporting the hypothesis of a catalytically active titanium imido intermediate.
