title: Fast "Wittig-like" reactions as a consequence of the inorganic enamine effect.
abstract: The tungsten alkylidyne [CF3-ONO]W≡CC(CH3)3(THF)2 (3) {where CF3-ONO = (MeC6H3[C(CF3)2O])2N(3-)} 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(O)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.
authors: Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States.
authors: Stella A
authors: SA
authors: Gonsales
authors: Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States.
authors: Matias E
authors: ME
authors: Pascualini
authors: Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States.
authors: Ion
authors: I
authors: Ghiviriga
authors: Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States.
authors: Khalil A
authors: KA
authors: Abboud
authors: Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States.
authors: Adam S
authors: AS
authors: Veige