Tetrabutylammonium cyanide

Cyano-de-diazoniations of the Sandmeyer type have been used for the synthesis of aromatic nitriles for many decades (example Clarke and Reed, 1964), as cyanide ions are comparable to bromide and iodide in many respects. A homolytic cyano-de-diazo-niation that does not use metal ions as reductant or ligand transfer reagent was described by Petrillo et al. (1987). They showed that substituted diazosulfides (XC6H4 — N2 — SC6H5), either isolated or generated in situ from arenediazonium tetrafluoroborates and sodium benzenethiolate, react with tetrabutylammonium cyanide in dimethylsulfoxide under photon stimulation, leading to nitriles (XC6H4CN). The method worked well with eleven benzenediazonium ions substituted in the 3- or 4-position, and was also used for the synthesis of phthalo-, isophthalo-, and tere-... 

The reaction between benzyl chlorides and tetrabutylammonium cyanide in tetrahy-drofuran at 20 °C is illustrated in Fig. 10.7. 

Versuche, aus 3-Brom-5-organo-l,2,4-oxadiazolen mit Kaliumcyanid 3-Cyan-l,2,4-oxadiazole zu erhalten, verliefen erfolglos142 321- Diese erhalt man aber aus 3-Diazoniono-l,2,4-oxadi-azolen mit Tetrabutylammonium-cyanid in Dimethylformamid32. ... 

Scheme 61, yielded thiazole 200 as the major product, along with minor amounts of carbinol 201 [152]. On the other hand, treatment of the imine formed from 199 and p-methoxyphenylamine with catalytic tetrabutylammonium cyanide, produced suc-cinimide derivative 202. In both cases, the process is initiated by nucleophilic attack to the carbaldehyde C=0 (or azomethine s C=N) group, which is followed up by an anionic rearrangement. A variation of the above process using as catalysts /V-heterocyclic carbenes (NHC) derived from base treatment of azolium, imidazo-lium, or triazolium salts, has also been developed to access gem-disubstituted succinimides [153, 154]. Unfortunately, an attempt of kinetic resolution of racemic 4-formyl (3-lactams by using chiral NHC resulted in moderate selectivities only [154]. 

Diastereoselectivities in the tetrabutylammonium cyanide-catalysed cyanosilylation of cyclic a -epoxyketones are dependent on ring size, with a switchover in selectivity between flve-membered and larger rings being explained through computation of... 

Tetrabutylammonium cyanide catalyses ring expansion of 4-(arylimino)methyl-azetidin-2-ones to 5-aryliminopyrrolidin-2-ones through a novel N(l)-C(4) bond cleavage of the /3-lactam nucleus and provides for an efficient one-pot protocol to enantiopure succinimide derivatives (Scheme 20).36... 

NCS)2] (51), and TBA[Ir(ppy)2(NCO)2] (52). These complexes were conveniently synthesized under inert atmosphere by reaction between the dichloro-bridged Ir dimer [Ir(ppy)2(Cl)]2 in dichloromethane solvent with an excess of a pseudohalogen ligand such as tetrabutylammonium cyanide, tetrabutyl-ammonium thiocyanate, or tetrabutylammonium isocyanate, respectively, with over 70% yields [77]. 

An intramolecular example is provided by the zirconocene-catalyzed cyclization of epoxy esters 222 to give bicyclic products 223 (Equation 82) <1997T16575>. When the closely similar fluorinated epoxy esters 224 are formed in situ, polymerization occurs to give poly(dioxolanes) (Scheme 22) <1999T6311>. Tetrabutylammonium cyanide catalyzes the isomerization of 225 to afford benzodioxoles 226 (Equation 83) <2004T3825>. 

Generally benzoins are generated by the action of sodium cyanide or potassium cyanide on aromatic aldehydes in aqueous ethanol via cyanohydrin intermediates. Benzoins may also be prepared in good yields by treating aromatic aldehydes with potassium cyanide in the presence of crown ethers in water or aptotic solvents. Other sources for cyanide in this type of condensation are tetrabutylammonium cyanide, polymer-supported cyanide and acetone cyanohydrin with KaCOs. Similarly, addition of aromatic ddehydes to a,3-unsaturated ketones can be accomplished by means of cyanide catalysis in DMF.7... 

The preparation of aromatic nitriles by an 5rn1 process was described recently.Suitably substituted diazo sulfides, either isolated or only generated in situ, reacted with tetrabutylammonium cyanide under photon or electron stimulation (equation 21), leading to aryl cyanides with yields that are comparable with those of the Sandmeyer reaction. Bromo- and chloro-substituted aryl diazo sulfides afforded the corresponding dinitriles in high yields. 

The thermolysis (- 10 to -t- 25°C) or photolysis (2 > 300 nm, - 10°C) of 3//-diazirine-3-car-bonitriles generates cyanocarbenes under very mild reaction conditions (see Houben-Weyl, Vol. E19b, pl206). Their addition to electron-rich alkenes yielded cyclopropane carbonitriles in moderate yields (Table 3). The 3//-diazirines-3-carbonitriles were prepared from 3-halodiazirines, mostly in situ, by an exchange reaction with tetrabutylammonium cyanide. The cyclopropanation of (Z)- or ( )-but-2-ene proceeded nonstereospecifically, which is explained by the participation of a triplet carbene. 

Table 25 The secondary a-deuterium, the secondary P-deuterium, the a-carbon UC/14C, the incoming group carbon 12C/13C, the nucleophile nitrogen and the chlorine leaving group KIEs found for the Sn2 reaction between ethyl chloride and tetrabutylammonium cyanide in anhydrous DMSO and THF at 30°C...

Die Reaktion von Tetrabutylammonium-cyanid mit dem Palladium-Komplex des Arylazo-naphthalins fiihrt nur unter Verwendung von l,2-Bis-[diphenylphosphano]-ethanzum Indazol, wahrend mit Triphenylphosphan lediglich l-Arylazo-2-cyan-naphthalin erhalten wird414. 

Variations in the Darzens procedure include the generation, from one phosphorylated carbanion, e.g. 359, of a second carbanion, 360 (similar to 358 already encountered in Scheme 30), as a prelude to the Darzens displacement to give 361W en treated with tetrabutylammonium cyanide, the ester 362 yields both the epoxide 363 and the cyanooxo ester 364". ... 

An unusual stereospecific ring contraction has been observed upon attempted substitution of 4-0-activated pentono-1,5-lactams with cyanide. The reaction of 4-0-methanesulfonyl-2,3-0-isopropylidene-D-ribo- or -D-lyxo-1,5-lactams with tetrabutylammonium cyanide gave 4-amino-5-C-cyano-4,5-dideoxy-2,3-0-iso-propylidene-L-lyxo- or -L-ribo-l,4-lactams respectively (Scheme 16), instead of the expected products of simple Sn displacement of mesylate by cyanide. Reduc-... 

Tetrabutylammonium cyanide Reactions with tetraalkylammonium salts Benzoins from aldehydes... 

Organic-inorganic contact can be improved by the use of tetraalkylammonium in place of alkali metal ions. - E A mixture of benzaldehyde, tetrabutylammonium cyanide, and water stirred ca. 1 hr. at room temp. benzoin. Y 70%. J. Solodar, Tetrah. Let. 1971, 287. 

What might account for the remarkable reactivity of the TBAF, reagent What might be a reason for the researchers choice of the highly toxic tetrabutylammonium cyanide as a starting material for synthesizing TBAFj j, ... 

Mizuno et al., reported a new photo-NOCAS reaction catalyzed by phenanthrene (145). Both of a catalytic amount of tetrabutylammonium cyanide and a cyanide anion eliminated from / -dicyanobenzene (144) were used as a nucleophile in this photoreaction. Yasuda et al., reported a temperature elfect of this photoreaction using flow-microreactor. The quantum yields for the formation of photo-NOCAS products were remarkably enhanced at lower temperatures. ... 

Diethylamine acetate Pyridinium salt Tetramethylammonium acetate, Tetraethyl-ammonium Tetra-butylammonium -Bis(tetra-n-butyl-ammoniumjoxalate Tetrabutylammonium cyanide... 

The nitrenic potential of l//-diazirines (165) has been further expanded. After the generation of various l//-diazirine (165)/imidoylnitrene (166) hybrids by simply reacting the corresponding 3-bromo-3//-diazirines (167) with diverse nucleophiles, their nitrenic behaviour has been demonstrated thanks to their observed reactivity towards phenylmagnesium bromide and tetrabutylammonium cyanide. Noteworthily, the first example of an imidoylnitrene C-H insertion has been aehieved in the course of this work. 

Sun and DiMagno demonstrated the rapid generation of Af-methyl-5-fluoro-4-nitroimidazole from the corresponding chloride using anhydrous TBAF that was generated in situ from KF by fluoride relay (Scheme 60) [75]. hi fluoride relay, the reaction of KF with 2,6-dicyano-tetrachlorobenzene transfers the fluoride to the arene that finally produces the activated anhydrous tetrabutylammonium fluoride (TBAF) upon the addition of tetrabutylammonium cyanide (>60 % yield from KF). Other polar aprotic solvents, such as THF and acetonitrile, are also effective for this SnAt fluorination reaction. 

Phase transfer catalysis found one of its earliest applications in cyanide displacement reactions. Starks studied this reaction in some detail and it was due in large part to his work that the concepts of phase transfer were so clearly understood at an early stage [1, 2]. There was, of course, other early interest in cyanide ion and these efforts should not be overlooked. Brandstrom had solubilized cyanide ion by his ion pair extraction technique [3] Solodar had facilitated the benzoin condensation by utilizing tetrabutylammonium cyanide [4] and Durst [5] and Liotta [6] both used crown ethers to phase transfer cyanide ion. A good deal of other work has now been carried out on phase transferred cyanide ion and is the subject of this chapter. 

In addition to the stoichiometric reactions of cyanide discussed above, phase transferred cyanide ion has been used as a catalyst in several organic reactions. Notable among these is the benzoin condensation which was facilitated by the presence of a catalytic amount of tetrabutylammonium cyanide. Thus, addition of a small amount of tetrabutylammonium cyanide to a 50% aqueous methanol solution at room temperature was found to effect the conversion of benzaldehyde to benzoin (Eq. 7.10)... 

The protection of carbonyl functions by reaction with trimethylsilyl cyanide to form the cyanohydrin trimethylsilyl ethers is subject to catalysis by potassium cyanide in the presence of 18-crown-6, tetrabutylammonium cyanide or resin bound tetraalkyl-ammonium cyanide [27, 29]. The nucleophilic cyanide ion is believed to attack the carbonyl yielding a cyanohydrin anion. This anion is silylated by trimethylsilyl cyanide with generation of an equivalent of cyanide anion. The sequence is shown in equation 7.13. Accordingly, 3-pentanone and 4- -butylcyclohexanone are cyanosil-... 

Many organic reactions which involve ionic species involve the cations associated with the reactive anions, even though most of the attention is focused on the latter. Some reactions, like the displacement of bromide by cyanide in the synthesis of a cyano-alkane [5] (see Eq. 7.2), appear to involve the cation in only the most peripheral way. In the above example, replacing sodium cyanide by tetrabutylammonium cyanide [6,7] or the 18-crown-6 complex of potassium cyanide does not alter the course of the reaction [8, 9], only its rate. There are, however, quite a few examples now available of alterations in the course of the reaction in the presence of crown ether, cryptate, or ammonium salts. 

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