Vanadyl trifluoride

A synthesis of ( )-tylophorine (213) has been based on the discovery that vanadyl trifluoride (VOF3) can be used to convert 1,2-diarylethylene into phenanthrenes in high yield. In the top sequence shown in Scheme 34, ring closure is accompanied by dehydrogenation (77CC826). In a second synthesis, ( )-tylophorine (213) is the result of an intramolecular version of a Diels-Alder cycloaddition of a conjugated diene with an imino dienophile (Scheme 34, lower sequence) (79JA5073). 

Pheuanthrene synthesis. Stilbene derivatives are oxidatively cyclized to phenanthrenes by vanadyl trifluoride in TFA-CH2CI2 at 0°. An example is the conversion of 1 into 2. This reaction had been conducted by photocyclization. 

Preparation of Aromatic Fluoro Derivatives. Reaction of (1) with Vp2, VF4, Vanadyl Trifluoride, or Xenon(II) Fluoride in HF, CFCI3, or MeCN at —30 to 20 °C yields mixtures of perfluoro-2,5-cyclohexadien-l-one together with its 2- and 4-pentafluorophenoxy derivatives and/or perfluoro-6-phenoxy-2,4-cyclohexadien-l-one, along with traces of perfluoro-2-cyclohexen-l-one or perfluoro-p-benzoquinone. Using Anti-mony(V) Fluoride or NbFa, however, only gives stable complexes or pentafluorophenolates, ... 

Sol in acet, tetrahydrofuran and eth acetate, si sol in n-heptane and methanol v si sol in toluene and w. Prepn of the initial polymer is from a dioxane soln at 50° of 2.0 equiv mol wts each of the monomers using either 1.5 equiv wt % of boron trifluoride etherate or 2.0 equiv wt % of vanadyl acetylacetonate as a catalyst to enhance the polymerization rate. Complete polymerization or gel is accomplished in about 70 hrs at 50°. The reaction rate is further enhanced by the addition of 0.072 equiv wt % of the isocyanate monomer after the initial reaction, resulting in gelation after 40 hrs at 50°. The hot dioxane soluble product is w pptd, vacuum steam-distd and dried. Post polymerization nitration of the polymer is accomplished with 100% nitric acid at 65°... 

The boron trihalide complexes with a number of phosphine sulphides and selenides can be isolated for the chloride, bromide, or iodide but, consistent with its reduced Lewis acidity, the trifluoride does not react.600 Alkyldithio-phosphonic acids give tin, lead, and mercury derivatives such as Me3SnSP-(S)FEt, Pb[SP(S)FMe]2, and MeHgSP(S)FMe, which are monomeric in solution, and there is n.m.r. evidence for a bidentate phosphonate group in the tin compound.601 Vanadyl chelates of alkoxy-ethyl and alkoxy-phenyldi-thiophosphonates (87) have been synthesized and e.s.r. measurements... 

Phenanthrenequinones. Substituted benzils undergo oxidative cycliza-tion on treatment with vanadyl fluoride and boron trifluoride etherate. The yields of the phenanthrenequinones range from 82% to 91% in 4 examples. 

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