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Stereochemically defined organofluorine compounds are vital to drug discovery and many applicable catalytic strategies have been introduced for accessing these entities stereoselectively. One approach entails incorporation of a fluorine atom (C−F bond formation) or an organofluorine moiety (e.g. CF3 or CF2H), and another exploits commercially available compounds with one or more fluorine atoms. Here, we present the state‐of‐the‐art regarding the use of alkenyl and allylic fluorides in preparation of stereochemically defined fluoro‐organic molecules. Allylic and alkenyl fluorides may be purchased or generated from a commercially available acid, carboxylate salt, ester, aldehyde hydrate, or ketone bearing several fluorine atoms next to a carbonyl group. We underscore the untapped potential of purchasable organofluorine compounds, many allylic and alkenyl fluorides, as launching points for development of stereoselective processes that are of value to therapeutic science. [ABSTRACT FROM AUTHOR]

The tungsten alkylidyne [tBuOCO]W≡C(tBu) (THF)2 ( l ) reacts with CO2, leading to complete cleavage of one C = O bond, followed by migratory insertion to generate the tungsten-oxo alkylidene 2. Complex 2 is the first catalyst to polymerize norbornene via ring expansion metathesis polymerization to yield highly cis-syndiotactic cyclic polynorbornene. [ABSTRACT FROM AUTHOR]

The tungsten alkylidyne [CF3-ONO]W ≡CC(CH3)3(THF)2 (3) {where CF3-ONO = (MeC6H3[C- (CF3)2O] )2N3-} supported by a trianionic pincer-type ligand demonstrates enhanced nucleophilicity in unusually fast "Wittig-like" reactions. Experiments are designed to provide support for an inorganic enamine effect that is the origin of the enhanced nucleophilicity. Treating complex 3 with various carbonyl-containing substrates provides tungsten-oxo-vinyl complexes upon oxygen atom transfer. The rates of reactivity of 3 are compared with the known alkylidyne (DIPP)3W ≡CC(CH3)3 (DIPP = 2,6-diisopropylphenoxide). In all cases (except acetone), complex 3 exhibits significantly faster overall rates than (DIPP)3W ≡ CC(CH3)3. New oxo-vinyl complexes are characterized by NMR, combustion analysis and single crystal X-ray diffraction. Treating 3 with acid chlorides provides the tungsten oxo chloride species [CF3-ONO]W(0)Cl (4) and disubstituted alkynes. In the case of acetone the oxo-vinyl complex results in two rotational isomers 10syn and 10anti( The rate of isomerization was determined for the forward and reverse directions and was complimented with DFT calculations. [ABSTRACT FROM AUTHOR]

The cleavage of carbon dioxide by the tungsten alkylidyne [CF3-ONO]W≡CCtBu(THF)2 (1) {where CF3-ONO = (MeC6H3[C-(CF3)2O])2N3−}, is reported. Splitting of CO2 yields the tungsten oxo ketene complex [CF3-ONO]W(O){(CH3)3CC=C=O} (6). The proposed pathway occurs through initial cycloaddition of W≡C and C=O bonds to generate a heterometallacyclobutene, which then rearranges to yield W≡O and C=C bonds. Complex 6 was characterized by multinuclear NMR, IR, and single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

The 2,6-di(1H-imidazol-2-yl)pyridine (H 2 dimpy) ligand is synthesized and suggested as an alternative ligand for copper mediated catalysis. A Cu(II) complex was obtained with this ligand and characterized via ESI-MS, FT-IR, UV–vis and the structure was confirmed by single crystal XRD. The crystal showed the [ Cu 2 ( H 2 dimpy ) 2 ( μ - Cl ) 2 ] ( PF 6 ) 2 · 2 H 2 O dimeric complex, in which Cu(II) is in a distorted square-pyramidal geometry ( τ = 0.301 ). Ferromagnetic coupling with J = - 11.1 cm −1 was confirmed by experiment and corroborated by density functional calculations. In order to evaluate the applicability of H 2 dimpy in atom transfer radical polymerization (ATRP), polystyrene was produced in DMF solution at low polydispersity (1.3) while maintaining the livingness of the polymer chain. The good performance of the H 2 dimpy compared to a standard ligand for ATRP (5,5′-dimethyl-2,2′-dipyridyl) indicates that it is suitable for this reaction. [ABSTRACT FROM AUTHOR]