Benzenediazonium fluoroborate

Benzenediazonium fluoroborate, 2-carboxy-xanthone synthesis from, 3, 838 Benzenediazonium ions phenyl azide formation from, 5, 839 Benzenediazonium salts, o-(imidazol-l-yl)-intramolecular diazo coupling, 5, 404 Benzene-1,2-disulfonimides N-substituted reactions, 6, 930 Benzene episulfide formation, 7, 577 Benzeneimine... 

Ionization. The pKa at 25° in w is 3.60, 50% aq et ale 4.11, et ale 7.5, and me ale 7.2 (Ref 17) Reactions. It reacts with benzenediazonium chloride to give yellow crysts, mp 75° with gas evolution, whose structure was first thought to be (PhN N)2C(N02)2 (Ref 3). More recently the reaction with p-nitro benzenediazonium fluoroborate was examined in greater detail (Ref 11). The first prod isolated was the hydrazone p-02NC6H4NHN C(N02)2, orange-red crysts, mp 120—25° with decompn. It deflagrates when heated on a spatula, and its solns decomp slowly in the cold and more rapidly on heating, with evolution of oxides of N. From the mother-liquor was obtained another compd, mp 164°, which was considered to be a meso-ionic compd ... 

In the context of this section it is important that Ruchardt and Tan (1970 a) found that (solid) benzenediazonium fluoroborate gave benzyne adducts with potassium acetate in the presence of aryne trapping agents such as tetracyclone or anthracene. This is, however, not the case if water is present (Cadogan, 1971). As a consequence of these observations, Cadogan et al. (1971) simplified the formation of arynes from diazonium ions by converting aniline or its substitution products into arynes in a... 

Decomposition of benzenediazonium fluoroborate in sulfolane causes an unusual O-phenylation a phenyl cation may be involved in the formation of the crystalline aryloxysulfonium salt (594) (77T2019). 

In a mechanistically similar process, the neutral palladium(II) dipyridylamine complex (24), obtained by deprotonation of complex (23), underwent reaction with benzoyl chloride to give the substituted complex (25) together with some free ligand (Scheme 8).33 This particular reaction sequence could not be generalized because of the relative instability of other metal complexes related to compound (24). However, a more extensive series of electrophilic substitutions could be carried out on the neutral complex (26), which displayed ambident nucleophilic behaviour by reaction with benzyl chloride and benzoyl chloride at nitrogen and reaction with benzenediazonium fluoroborate at carbon (Scheme 9). 

The 2-pyridylhydrazone of pyridine-2-carbaldehyde yields tridentate metal complexes which can be deprotonated to neutral complexes (81).175-177 These in turn can be reprotonated, alkylated or acylated on nitrogen and reacted with benzenediazonium fluoroborate on carbon (Scheme 33).178... 

Dissolve 46.5 g (45.5 ml, 0.5 ml) of aniline in a mixture of 126 ml of concentrated hydrochloric acid and 126 ml of water contained in a 1-litre beaker. Cool to 0-5 °C in a bath of ice and salt, and add a solution of 36.5 g (0.53 mol) of sodium nitrite in 75 ml of water in small portions stir vigorously with a thermometer and maintain the temperature below 10 °C, but preferably at about 5 °C by the addition of a little crushed ice if necessary. The diazotisation is complete when a drop of the solution diluted with 3-4 drops of water gives an immediate blue coloration with potassium iodide-starch paper the test should be performed 3-4 minutes after the last addition of the nitrite solution. Prepare a solution of 76 g (0.69 mol) of sodium fluoroborate (1) in 150 ml of water, cool and add the chilled solution slowly to the diazonium salt solution the latter must be kept well stirred and the temperature controlled so that it is below 10 °C. Allow to stand for 10 minutes with frequent stirring. Filter the precipitated benzenediazonium fluoroborate with suction on a Buchner funnel, drain well and wash the yellow solid with about 30 ml of ice-water, 15 ml of methanol and 30-40 ml of ether suck the solid as free as possible from liquid after each washing (2). Spread the salt upon absorbent filter paper and allow to dry overnight, if possible in a current of air. The yield of benzenediazonium fluoroborate is 60—65 g the pure salt melts with decomposition at 119-120 °C. 

Annelation of steroidal dienamines with substituted phenacyl bromides (7 examples) or with benzenediazonium salts (11 examples) has been shown to lead to the corresponding furano- and indolo-steroids.89 Thus the A3,5-dienamine derived from A4-androstene-3,17-dione reacted with p-bromophenacyl bromide to yield the A5-androstano[3,4-h]furan (199) in 26% yield, and reaction of the same A3,5-dienamine with benzenediazonium fluoroborate at -45 °C led to formation of the hydrazone (200) which underwent Fischer-indole cyclization on treatment with phosphorus oxychloride to produce the A4-androstano[6,7-6]indole (201). The A3,5-dienamine derived from 17/3-acetoxyandrost-4-en-3-one has been converted into the benz[4,5,6]-steroid (202 R1 = Me, R2 = H) by reaction with methyl vinyl ketone and into the analogous benzsteroid (202 R1 = H, R2 = Me) on treatment with crotonal-dehyde.90 A route to the condensed pyrroline ring system (203) has been devised... 

In the presence of pyridine or KF at — 40°C, HNF2 reacts with benzenediazonium fluoroborate to give o-fluorophenylazide, p-fluoro-phenylazide, and benzene (19). 

Cycloaddition of phenyl isothiocyanate (296) to pyridinium salts (295) produced imidazo[l,2-a]pyridine-2(3//)-thiones (297) (77Ml4looi). Reaction of l-aryl-2-chloropyridin-6-ones with mono-A/ -substituted ethylenediamines provided dihy-droimidazo[l,2-a]pyridin-5-ones (79CPB1207). Another procedure involves the polyphos-phoric acid cyclization of 2-(2-hydroxyethyl)aminopyridines (76AJC1039). Treatment of certain /3-aminoacrylic esters (298) with benzenediazonium fluoroborate (299) resulted in... 

Schiemann and related displacements. Addition of an ice-cold solution of fluoro-boric acid to a vigorously stirred solution of benzenediazonium chloride at 0° gives a yellowish crystalline precipitate of benzenediazonium fluoroborate, which is collected, washed with ice water, methanol, and ether, and dried. The solid is... 

Benzenediazomum-2-carboxylate, 46,1194 Benzenediazonium chloride, 394, 838 Benzenediazonium fluoroborate, 394 Benzenediazonium nitrate, 328 Benzenediazonium sulfonate, 713 Benzene-maleic anhydride 1 2 adduct, 557 Benzenesulfinyl fluoride, 849 Benzenesulfonamides, 46-47, 48... 

Reaction with diazonium sdts. Curtin and Tveten found that reagent prepared by either method reacts with a benzenediazonium fluoroborate in dimethylformamide to give a trans-azo compound in high yield. However, when diphenylzinc prepared... 

The classical diazonium salt route to phenolic ethers has been re-examined. The slow addition of methoxytrimethylsilane (4 moles) to benzenediazonium fluoroborate in ice-cold freshly distilled Freon-113 under nitrogen, warming of the mixture to 55°C with ultrasonic agitation (W-385 processor) and finally refluxing with continued sonication at the same temperature during 16 hours, afforded a 51% yield of anisole (ref.71). 

It was found that 1,3-diethoxycarbonylallene 231 readily enters [4 -I- 2] cycloaddition with heterocyclic dienes. The adduct (232) obtained from 231 and furan was easily converted into ketoester 233. Treatment of the latter compound with lithium diisopropylamide and benzenediazonium fluoroborate resulted in the formation of the a-phenylazo compound 234, which in turn underwent sodium borohydride promoted scission of carbon-carbon bond affording the C-glycosylic compound 235 ... 

Cationic polymerizations of allyl esters require further investigation. Schild-knecht [7] mentions the polymerization of allyl acetate and of allyl formate in benzene solution upon heating the solution with 6% of benzenediazonium fluoroborate under nitrogen at 200°C in sealed tubes. The solid products melt at about 190°C (d) and are soluble in benzene and insoluble in methanol. 

N-Benzylideneaniline treated with an equivalent amount of nitrosyl fluoroborate in acetonitrile -> benzenediazonium fluoroborate. Y almost 100%. Also formation of carbonium ions by reaction of nitrosyl fluoroborate with azides s. M. P. Doyle and W. Wierenga, Am. Soc. 92, 4999 (1970). 

Solid sodium boron hydride added in small portions to chilled o-carboxy-benzenediazonium fluoroborate in methanol, and the resulting soln. poured cautiously on ice-HCl benzoic acid. Y 77%. F. e., also in dimethylformamide, s. J. B. Hendrickson, Am. Soc. 83, 1251 (1961). 

A soln. of benzenediazonium fluoroborate in acetone added dropwise at 0° under Ng during 3 hrs. to a soln. of K-triphenylcyanoborate in dry acetone N-phenyl-azotriphenylcyanoboron betaine. Y 64%. - This is the first known compd. with a N-diazonitrilium group. E. Brehm, A. Haag, and G. Hesse, A. 737, 80, 70 (1970). 

Primary aromatic amines and their N-mono- and N,N-dialkyl derivatives can be coupled with diazonium salts in a slightly acid medium. The reaction can be carried out using stabilized diazonium salts (which do not contain free nitrous acid), for example, with p-nitrobenzenediazonium fluoroborate (17) or with a salt with 1-naphthalenesulfonate. The reaction takes place in dilute acetic acid in the presence of sodium acetate. Recently, 4-azo-benzenediazonium fluoroborate was proposed as the reagent, and dimethyl sulfoxide or dimethylformamide (18, 19) as the reaction medium in which intensely colored di-cations of bis-azo dyes can be formed. 

Benzylidene-) -naphthylamine treated 0.5 hr. at room temp, with p-methoxy-benzenediazonium fluoroborate in acetonitrile benzylidene-a-(p-methoxy-phenylazo)-j -naphthylamine hydrofluoroborale (Y 81%) treated with pyridine N-p-methoxyphenyl-2-phenylnaphth[l,2-d]imidazol-l-ylamine (Y 88%). F.e., also without isolation of the intermediate, and limitations, s. A. Messmer and O.Szim n, Ang. Gh. 79, 237 (1967). 

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