Nitrosyl fluoride, reaction

Two distinct reactions are described between 9(ll)-enes (148) and nitrosyl fluoride. Reaction at 3°C in dichloromethane gave the 9a-fluoro-ll-nitrimino-derivative (149), hydrolysed on passage through alumina to give the fluoro-ketone... 

Arsenic trifluoride (arsenic(III) fluoride), AsF, can be prepared by reaction of arsenic trioxide with a mixture of sulfuric acid and calcium fluoride or even better with fluorosulfonic acid. Chlorine reacts with ice-cold arsenic trifluoride to produce a hygroscopic soHd compound, arsenic dichloride trifluoride [14933-43-8] ASCI2F35 consisting of AsQ. and AsF ions (21). Arsenic trifluoride forms a stable adduct, 2AsF2 SSO, with sulfur trioxide and reacts with nitrosyl fluoride to give nitrosonium hexafluoroarsenate(V) [18535-07-4] [NO][AsFg]. 

Boswell,making use of the methodology elaborated by Martin and Kagan, prepared a series of 6,6-difluoro-A -3-ketones closely related to the steroid hormones, exemplified by the conversion of 3)5,17a-dihydroxypregn-5-en-20-one diacetate (7) to 6,6-difluoro-17a-acetoxyprogesterone (12). Reaction of (7) with nitrosyl fluoride at 0° affords the nitrimine (8), which is... 

The reactions of A -steroids with nitrosyl fluoride parallel those of their A -isomers. Thus, 17 -acetoxyandrost-4-ene (37) is converted to the nitrimine (38), in 67 % yield and thence to the 4-ketone (39), which can be dehydrofluorinated to the A -4-ketone (40) with lithium bromide in di-methylformamide. In the corresponding 19-nor series the nitroso dimer is also formed. 

The reaction of 9(1 l)-dehydro steroids with nitrosyl fluoride was studied by Grantz and Rosenthal in pursuit of an alternate source for the important 9a-fluoro-11-oxygenated steroids. As expected, reaction at the more hindered 9(1 l)-double bond proceeds more slowly than at either the 4- or 5-double bonds. After 10 days at 3°, 3 -acetoxy-5a-pregn-9(l l)-en-20-one (50) affords a 45% yield of the 9a-fluoro-ll-nitrimine (51). Other 9a-fluoro-ll-nitrimines were prepared and it was found that the presence of additional keto groups, particularly the 3-keto group gives rise to side products with a concomitant reduction in yield of the desired 9a-fluoro-ll-nitrimines. In the case of the A" -3-ketones the yield is reduced to 10 %. The steric hindrance... 

Mechanism The reaction of and A -steroids with nitrosyl fluoride to form ni trimines is best discussed in conjunction with the nitrosyl chloride reaction leading tothe5a-chloro-6 -nitro steroids (33). Since nitroso alkanes are oxidized with nitrosyl chloride to nitro alkanes it is believed that 5a-chloro-6j5-nitro steroids are formed in this way from an initially formed 5a-chloro-6 -nitroso adduct. The same is true for nitrosyl fluoride up to the stage of the nitroso fluoride (56). Since NOF is a weaker oxidizing agent than NOCl the nitroso fluoride tautomerizes to the fluoro oxime (57) at a rate... 

Nitrosyl fluoride reacts with steroidal olefins to give, ultimately, a-fluo-roketones [131], with steroidal vinyl lluorides, the reaction provides a,a di fluoroketones from intermediate nitroimines [197] (equation 34)... 

The scheme required to prepare the potent tri-fluoro corticoid cormethasone acetate (292) illustrates the synthetic complexities involved in some of this work. Sequential acetylation of the pregnenolone derivative 278 with first acetic anhydride in pyridine and then acetic anhydride in the presence of tosic acid affords diacetate 279. Reaction of that intermediate with nitrosyl fluoride results initially in addition of the reagent to the 5,6-olefin moiety to afford the fluoro oxime reaction with a second mole of reagent at nitrogen gives the nitroimine derivative 280 passage over alumina serves to hydrolyze the imine function to the corresponding 6-ketone (281). 

Nitration of the amine (139) with mixed acid yields the energetic nitramine (140). The same reaction with sodium nitrite in sulfuric acid, or with nitrosyl fluoride in methylene chloride, yields the nitrosamine (141), which is also an energetic high explosive. ... 

Nitrosyl fluoride may be prepared by the reaction of fluorine with nitric oxide ... 

Nitrosyl fluoride is a dangerous irritant to the eyes, skin, and mucous membranes. Explosive reactions can occur with alkenes. 

M. Welch, J.F. Litton, P.P. Caspar, Production of F for bone scanning from the 2°Ne(d,alpha) F reaction via fluorine-18 labeled nitrosyl fluoride. A selective fluorinating agent, J. Nucl. Med. 12 (1971) 405. 

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... 

A number of hexahalogenotellurates(IV) have been investigated. A few rather unstable hexafluoro complexes are known, for example the nitrosonium compounds of composition (NO)2XF6 have been obtained40 from the reaction of nitrosulfuryl fluoride, NOS02F, with selenium or tellurium tetrachloride. The selenium compound loses nitrosyl fluoride at room temperature to leave the pentafluoroselenate(lV), whereas the tellurium analogue remains... 

Over the last 15 years many new reactions of nitrosyl fluoride with a variety of fluorides and oxide fluorides have been studied but no new types of reaction have been observed. The recent work is discussed below. 

In 1967 POF3 was reported to react with cesium fluoride to give Cs+[P02F2] and Cs+[PF6] (86). More recent work by Selig and Aminadav (59) has shown that reaction with alkali metal and nitrosyl fluorides in a 1 1 ratio yields [PF6] as the only fluorine-containing species. Primary and secondary negative-ion formation observed in the... 

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). 

Finally, the following reaction of nitrosyl fluoride, NOF, with C1F is noteworthy ... 

The phosphorus analogue of nitrosyl fluoride, POF, is formed by the reaction between POFBr2 and silver and has been characterized by matrix isolation infrared spectroscopy and by mass spectrometry [34], Ab initio calculations and a normal... 

The reaction of unsaturated steroids with nitrosyl fluoride leads to fluoro-substituted nitrimines 1 which arc hydrolyzed to a-fluoro ketones 2. ... 

Trifluoroamine oxide, ONF3, bp —87.6 °C, can be made by fluorination of nitrosyl fluoride with IrFs or reaction of NO with F2. F3NO is stable in glass at 11°C and is kinetically much less reactive than FNO and FNO2. Most reactions involve reaction of F3NO with strong Lewis acids to form ONF2+ salts. 

Nitric oxide forms nitrosyl halides in the reaction with chlorine and bromine (see Section 9.1) in the reaction with fluorine, both nitrosyl fluoride and trifluoramine oxide are formed (see Section 9.3). 

Nitrosyl fluoride was also made from NO2 and C0F3 and by the reaction of nitryl chloride with hydrogen fluoride ... 

ONF3 is also accessible from the reaction of nitrosyl fluoride with iridium hexafluoride ... 

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