Oxidation tetrafluoroborate

Wallis and Dunitz (1984a) also investigated another type of sterically induced interaction of a donor group with a diazonio group. Quinoline-8-diazonium-l-oxide tetrafluoroborate (4.14) was analyzed at 95 K (R = 0.034). 

OXYAMINATION Mercury(ll) oxide-Tetrafluoroboric acid. Trioxn(/-butyl-imido)osmium (VIII). 

S)-(—)-Menthyl p-toluenesulfmate, 312-315 Mercury(II) acetate, 315-316 Mercury(II) nitrate, 317-318 Mercury(II) oxide-boron trifluoride, 318 Mercury(TI) oxide-tetrafluoroboric acid, 318-319... 

Mercury(II) oxide-Tetrafluoroboric acid, HgO-HBp4, white, hygroscopic solid. 

The principal electrophiles to attack ring sulfur are either oxidants or alkylating reagents. Thiophene sulfoxide and sulfone formation is discussed in Section 3.02.2.6. Alkylating agents capable of forming thiophenium salts include trimethyloxonium tetrafluoroborate (MeaO BF ) and alkyl fluorosulfonates (ROSO2F). The salts e.g. 87) are conveniently isolated as hexafluorophosphates (88). 

Thiiranium salts, l-methyI-2-methylene-1-oxide, 7, 134 Thiiranium salts, I-phenyl-collisional activation spectra, 7, 135 Thiiranium tetrafluoroborate, 2,3-di-t-butyl-l-methyl-inversion barriers, 7, 134 Thiiranium ylides formation, 7, 174, 175 Thiiran-2-ones... 

Fluorine and nitrogen may be added to olefins with the nitrogen in different oxidation states Fluorine and a nilro group are added by reaction of an olefin with nitryl fluoride [131], nitronium tetrafluoroborate [195] (equation 32), or a combination of nitric acid and hydrogen fluoride [131, 196] (equation 33)... 

Reaction of [Ir(rj -cod)(/x-pz)]2 with nitrosyl tetrafluoroborate yields 140 (L2 = cod), the cationic nitrosyl complex [85JCS(CC)908]. The 3-methylpyra-zolato complex reveals the same type of behavior, while 3,5-dimethylpyrazolato derivatives give a different kind of product Oxidation of [Ir( j -cod)(/i,-pz )]2 with nitrosyl tetrafluoroborate or hexafluorophosphate leads to 141 (X = BF4, PFg). 

Another means of in situ metal-carbene complex formation in an ionic liquid is the direct oxidative addition of the imidazolium cation to a metal center in a low oxidation state (see Scheme 5.2-2, route b)). Cavell and co-workers have observed oxidative addition on heating 1,3-dimethylimidazolium tetrafluoroborate with Pt(PPli3)4 in refluxing THF [32]. The Pt-carbene complex formed can decompose by reductive elimination. Winterton et al. have also described the formation of a Pt-car-bene complex by oxidative addition of the [EMIM] cation to PtCl2 in a basic [EMIM]C1/A1C13 system (free CP ions present) under ethylene pressure [33]. The formation of a Pt-carbene complex by oxidative addition of the imidazolium cation is displayed in Scheme 5.2-4. 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

In the case of 2,3-dihydro-l-benzothiepin 1-oxide (5), alkylation with iodomethane and silver (I) tetrafluoroborate leads to the methoxysulfonium salt 6 in 65% yield.86... 

Nitration with concentrated nitric acid degrades chlorins which are sensitive to oxidation. Here nitronium tetrafluoroborate in sulfolane is the reagent of choice. Both mononitrooc-... 

The agents used for oxidative aromatization of various thiopyrans were air-dioxygen (81KFZ38 83KGS1689 91KGS181), trityl tetrafluoroborate (81CC1143 85CL1119), 3,4-di-(/-butyl)-l,2-benzoquinone (DTBQ)... 

The most important results are given in Figure 4-1. The oxygen atom lies 244 pm from the N(l) atom of the diazonio group, well within the sum of the van der Waals radii. The diazonio group deviates by 10.4° from linearity. It seems that the 0(1) N(l) interaction is attractive, as indicated by the angle of 169.6° (instead of 180°) at N(l), but the 0(1) N(2) interaction is not. The NN distance (109.9 pm) is, however, not different from normal values found in diazonium ions. The same authors demonstrated later (Wallis et al., 1993) that this result is not unique for the quino-line-8-diazonium-l-oxide salt, as it was found also for two 1-naphthalenediazonium tetrafluoroborates substituted in the 8-position with the electron donors -SCH3 and -N(CH3)2 and - perhaps unexpectedly - for 8-nitronaphthalene-l-diazo-... 

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