Nitrosyl tetrafluoroborate, reaction with

Reaction with olefins Nitrosyl tetrafluoroborate reacts with primary or secondary olefins in acetonitrile to give 2-methyl-N-hydroxyimidazolium salts (1) at -15 to 0°. 

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). 

Monosubstituted hydrazines treated with nitrous acid give azides in a reaction exactly analogous to the formation of aliphatic diazo compounds mentioned in 12-47. Among other reagents used for this conversion have been N204 ° and nitrosyl tetrafluoroborate (NOBp4). ... 

Reaction of vinyl azides with nitrosyl tetrafluoroborate gives furazans in good yield, particularly when the alkene is 1,2-dialkyl-substituted. For example, 1-azidocyclooctene and 2-azidobut-2-enes yield (19 n = 6) and (1, R1 = R2 = Me), respectively 1,2,4-oxadiazoles may also be formed as by-products. 

Tertiary hydrogens in substrates which readily form carbocations. such as adamantane, dimantane, and triphenylmethanc, are selectively fluorinated by treatment with a mixture of nitrosyl tetrafluoroborate and 70% hydrogen fluoride in pyridine in excellent yield.28 This reaction has been extended to secondary hydrogens /( to a bromine atom in a series of bro-moalkanes, e.g. fluorination of bromocyclohexane to give nwi.y-1 -bromo-2-fluorocyclohcxane (8).26... 

As the cofacial dimer 1 is a readily available compound, the best method for the preparation of thiatriazinium salts is to treat 1 with nitrosyl tetrafluoroborate or hexafluorophosphate. The reaction mixture must be kept under inert gas during the evolution of nitrogen oxide. A direct method is the reaction of 1-fluorothiatriazines, e.g. 3, with arsenic(V) fluoride or phosphorus pentafluoride. The so-called silver salt method consists of the reaction of 1-chlorothia-triazincs with silver(I) hexafluoroarsenate in liquid sulfur dioxide. 

Benzotriazine 1,3-dioxide (2 a) was prepared in 65% yield by treating the phenyldiazene oxide 1 with nitrosyl tetrafluoroborate in acetonitrile and then with 3-chloroperoxybenzoic acid in pyridine,34 or by reacting 1 with dinitrogen pentoxide in nitromethane or dichloromethane.34 The in situ occurring reaction of 1 with nitric acid and sulfuric acid led to the isolation of the nitro derivatives 2b-d.33... 

Sterically hindered carboxamides and sulfonamides can be deaminated in high yields by NO[BF4].578 For this reaction the nitrosyl tetrafluoroborate is dissolved in acetonitrile, treated, with stirring, with a solution of the amide in acetonitrile, and warmed until evolution of nitrogen stops. 

A Schlenk-type apparatus, illustrated in Fig. 1, is used for the synthesis. This apparatus is similar to that employed in other syntheses but allows for multiple filtrations of the reaction solution and manipulation of the complex in a completely sealed system. In a nitrogen glove box, a 100-mL round-bottomed flask (B) is charged with 1.0 g (9.4 nunol) of palladium sponge (99.95%, Johnson Matthey) and 2.2 g (18.8 mmol) of nitrosyl tetrafluorobor-ate (Aldrich, sublimed 220°C, 10 torr). This flask is connected to a medium... 

Mercuric acetate and mercuric trifluoroacetate are the usual reagents. The synthetic utility of the mercuration reaction derives from subsequent transformations of the arylmercury compounds. As indicated in Section 7.3.3, arylmercury compounds are only weakly nucleophilic, but the carbon-mercury bond is reactive toward various electrophiles. The nitroso group can be introduced by reaction with nitrosyl chloride or nitrosonium tetrafluoroborate as the electrophile. Arylmercury compounds are also useful in certain palladium-catalyzed reactions, as discussed in Section 8.2. 

Alkyl nitrites can also be used in anhydrous media and, for example, 4-hydroxyben-zenediazonium tetrafluoroborate is isolated in 89% yield after diazotization with isopcntyl nitrite, hydrogen fluoride and boron trifluoride in ethanol/diethyl ether.96 Diazotization can also be performed in dichloromethane or ethers (diethyl ether, tetrahydrofuran, 1,2-dimethoxyethane) with terl-butyl nitrite and boron trifluoride-diethyl ether complex which generates nitrosyl fluoride in situ.229 Excess boron trifluoride is used to trap water and tert-butyl alcohol, so that the reaction can be considered as being performed under complete anhydrous conditions. Yields are higher in dichloromethane, but 1,2-dimethoxyethane is preferred for less soluble amines. This procedure has been successfully applied to the synthesis of mono-and difluorobenzo[c]phcnanthrenes.230... 

Treatment of some a-ethynyl acetates with a mixture of nitrosyl fluoride and nitrosonium tetrafluoroborate affords bis[(acetoxyalkyl)carbonyl]furoxans the presence of the a-acetoxy group appears to be essential (81JOC312). Monosubstituted furoxans have been obtained by nitrosation of unsaturated hydrocarbons thus the reaction of nitrous acid with p -hydroxycin-namic acid affords 3-(p-hydroxyphenyl)furoxan, its structure being confirmed by X-ray crystallography (80LA1557). 

Nitrosyl hydrogen sulfate adds to aikenes at -40 C in liquid SO , in Markovnikov fashion giving 2-sulfato-oximes (37-84%).Reactions of nitrogen oxides with aikenes are usually complex, yet some have limited industrial, rather than laboratory, importance. Nitryl tetrafluoroborate in acetic anhydride at -65 to -45 C adds Markovnikov fashion to aikenes, with only fair stereoselectivity, giving 3-ni-troacetates in 36-40% yields. Nitryl fluorosulfonate adds to perfluoroalkenes in fluorosulfonic acid/ffeon-113 giving 63-92% 0-nitroperfluoroalkyl fluorosulfonates. 

Alkylation of thioamides with Meerwein s reagent (trialkoxonium fluoroborate) proceeds via a thioiminoester and subsequent base hydrolysis with sodium carbonate (equation 32). For the synthesis of 2-pyridones from 2-thiopyridones, chloroacetic acid has been used. ° Mild reaction conditions are provided by nitrosyl species which are derived from a variety of reagents excess NaNOa/HCP in aqueous medium, nitrosonium tetrafluoroborate in dichloromethane, dinitrogen tetroxide in acetonitrile at low temperature and f-butyl thionitrate. ... 

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