Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex

• Henrike Ehrhorn,
• Janin Schlösser,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2018, 14, 2425–2434, doi:10.3762/bjoc.14.220

• Henrike Ehrhorn Janin Schlosser Dirk Bockfeld Matthias Tamm Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany 10.3762/bjoc.14.220 Abstract The molybdenum and tungsten complexes M2(OR)6 (Mo2F6, M = Mo, R = C(CF3)2Me

• initially monitored over time through gas chromatography, affording the conversion versus time diagram depicted in Figure 4. Figure 4 clearly shows that both tungsten complexes are active in the metathesis of 1-phenyl-1-propyne, with the bimetallic compound W2F3 (grey) showing a slower initiation rate

• for various self-metathesis and RCAM reactions. These findings are in line with our initial results regarding the conversion of 1-phenyl-1-propyne (Table 2, entry 1). Both tungsten complexes afforded excellent yields in the metathesis of different para-substituted phenylpropynes (Table 2, entries 2–4

Is the tungsten(IV) complex (NEt₄)₂[WO(mnt)₂] a functional analogue of acetylene hydratase?

• Matthias Schreyer and
• Lukas Hintermann

Beilstein J. Org. Chem. 2017, 13, 2332–2339, doi:10.3762/bjoc.13.230

• acetylene. A critical assessment of, and a possible explanation for the earlier reported results are offered. The title question is answered with "no". Keywords: acetylene hydratase; alkynes; catalytic hydration; enzyme models; tungsten complexes; Introduction In 1985, the enzyme acetylene hydratase

• hydration activity was quite surprising and the enzymatic reaction mechanism was not immediately evident, for simple tungsten complexes had not been known to bring about alkyne hydration. The situation changed 1997 by a report of Sarkar et al. who described the activity of complex 1 for acetylene hydration

On the mechanism of imine elimination from Fischer tungsten carbene complexes

• Philipp Veit,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2016, 12, 1322–1333, doi:10.3762/bjoc.12.125

• mechanistic studies to the formation of imine E-3 are performed by NMR, IR and UV–vis spectroscopy and liquid injection field desorption ionization (LIFDI) mass spectrometry as well as by trapping experiments for low-coordinate tungsten complexes with triphenylphosphane. W(CO)5(E-2) decays thermally in a

• tungsten complexes M(CO)4/5(10), (M = Mo, W) eliminate two equivalents of propene giving the imine complexes M(CO)5(11). Formation of the imine complex tungsten(benzoxazole)(pentacarbonyl) W(CO)5(13) has been reported by Tamm and Hahn during the synthesis of the carbene complex tungsten(benzoxazolin-2

• resonances are found in a similar region as for other (pentacarbonyl)tungsten complexes W(CO)5(E-14R) with the α-ferrocenyl NH carbene ligand :C(NHR)Fc E-14R (R = Me, Et, n-Pr [23], n-Bu [25], n-Pent [21]). Due to additional ring-current effects and non-classical NH···Fe hydrogen bonding [54][55][56][57][58

Light-induced olefin metathesis

• Yuval Vidavsky and
• N. Gabriel Lemcoff

Beilstein J. Org. Chem. 2010, 6, 1106–1119, doi:10.3762/bjoc.6.127

• early beginnings of light induced olefin metathesis by the use of ill defined tungsten complexes, up to the most recent developments in light induced ruthenium based isomerisation and activation. Review Early tungsten catalysed photometathesis The first examples for photoinitiated metathesis were

• phenylacetylene. These works were based on earlier observations by Katz et al. [56][57] and Geoffrey et al. [58] that acetylenes irradiated in the presence of tungsten complexes form metal carbenes that can produce polymeric species. Well-defined tungsten catalysed photometathesis The first example of well