Anions tosyl cyanide

Iodonium salts 60 react with cyanide anion affording the cyano derivatives of crotonic acid 61 as single isomers retaining the initial configuration of the phenyliodonium tosylate (Scheme 28) [51]. 

Step 5 Sn2 displacement of the tosylate group with cyanide anion provides the TM. 

Halide and Azide Anions. These also open the epoxide re-gioselectively at the C-3 position. Addition of Li2CuBr4 results in bromide addition at the C-3 position of rac-(l), forming 3-bromo-1,2-propane 1-0-tosylate in 70-76% yield in THF or acetonitrile at It, or 1,3-dibromo-2-propanol in 82% yield in refluxing acetonitrile. Hydrofluorination takes place with KHF2 under solid-liquid phase transfer conditions, but the yield of fluorohydrin is very low (eq 3). Azidotrimethylsilane adds in the presence of a Lewis acid catalyst (eq 3). Addition of cyanide ion is achieved by using Diethylaluminum Cyanide in toluene. ... 

The alkylation chemistry of a considerable number of O-trimethylsilyl cyanohydrins derived from aryl and heteroaryl aldehydes has been reported by Hunig and coworkers. Tbe protected cyanohydrins are easily prepared by heating the aldehydes with trimethylsilyl cyanide in the presence of a Lewis acid. The use of dialkyl sulfates and tosylates as alkylating agents was so reported. Hata et alP failed to alkylate the anion of the adduct of trimethylsilyl cyanide and acetaldehyde, suggesting that the trimethylsilyl group is incompatible with the more basic anions derived from aliphatic aldehydes. Ficini et alP... 

Glass and Hoy have reported that treating an N-tosyl imine derived from an aromatic aldehyde with cyanide in HMPT leads to aryl nitriles in generally good yields [96]. It was proposed that this transformation might involve intermediates shown in Eq. (68). Alternatively, a dianion corresponding to the mono anions shown could be involved here. 

The major method for cation photogeneration involves photoheterolysis of carbon-heteroatom bonds leading to formation of carbocations and the heteroatom anionic leaving group [Eq. (6)] [5,6,51]. Leaving groups have included halide, acetate, hydroxide, tosylate, 4-cyanophenoxide, cyanide, and phosphonium chloride. 

KCN and calefaction of the mixture. Under these conditions, the cyanide anion is added to the carbonyl group and the high temperature promotes the elimination of the hydrazine moiety. The use of trisylhydrazones instead of the tosyl analogs reduces the temperature required, giving rise to nitrile derivatives in good yields. This transformation has been utilized in tbe isotopic labeling of metabolites (eq 28). 

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