Cyanosilanes

Cyanosilylations of carbon-oxygen and carbon-nitrogen double bonds with cyanosilanes are very important synthetic reactions since the products, cyanohydrin silyl ethers and a-amino nitriles, serve as synthetic intermediates for a variety of natural products. A number of studies on these subjects have been reported in the last decade however, this review does not deal with carbonyl and imine cyanosilylations due to the availability of recent reviews and limited 

The Lewis acid-catalyzed reaction of epoxides with cyanotrimethylsilane (Me3SiCN) forms /3-siloxy nitriles.252 Highly enantioselective desymmetrization of / -epoxides with Me3SiCN can be achieved by chiral Ti and Yb catalysts (Equation (67)).255 256 

Me3SiCN is a convenient, reactive cyanide donor in transition metal-catalyzed processes. The Pd-catalyzed reaction of aryl iodides with Me3SiCN is useful for the synthesis of aryl cyanides.257 Me3SiCN works also as an effective co-catalyst for the Pd-catalyzed cyanation of aryl iodides with KCN.258 Allylic acetates, carbonates, and the related compounds undergo the Pd-catalyzed cyanation with Me3SiCN.259-261 The tandem cyclization-cyanation reaction of 2-bromo-l,6-heptadienes with Me3SiCN proceeds under catalysis by an Ni complex (Equation (68)).262 

Cyanosilylation of alkynes with Me3SiCN is effectively catalyzed by a PdCl2 complex.263 Its intramolecular version is valuable for the stereo-defined synthesis of tri- and tetrasubstituted alkenes.264 A Pd-catalyzed system effects an efficient three-component coupling of Me3SiCN, highly electron-deficient alkenes, and allyl chlorides (Equation (69))/ 3 The 

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Cyano compounds liquid crystals, 12, 278 in silver(III) complexes, 2, 241 Cyanocuprates, with copper, 2, 186 Cyano derivatives, a-arylation, 1, 361 Cyanosilanes, applications, 9, 322 Cyclic acetals, and Grignard reagent reactivity, 9, 53 Cyclic alkenes, asymmetric hydrosilylation, 10, 830 Cyclic alkynes, strained, with platinum, 8, 644 Cyclic allyl boronates, preparation, 9, 196 Cyclic allylic esters, alkylation, 11, 91 Cyclic amides, ring-opening polymerization, via lanthanide catalysis, 4, 145... 

Cyanosilanes can be isocyanide sources since a tautomeric equilibrium exists between cyanosilanes and the corresponding isocyanides. The equilibrium largely favors the cyano tautomer. The use of such dilute isocyanide donors realizes efficient Ti(n)- and Ni(0)-catalyzed cyclizations of enynes to iminocyclopentenes via metallacyclopentene intermediates (Scheme 19).266,266 266b Treatment of zirconacyclopentanes and -pentenes with Me3SiCN provides zirconocene-imine complexes, which serve for carbon-carbon bond formation with various unsaturated bonds.267... 

A. J. L. Pombeiro, D. L. Hughes, C. J. Pickett, and R. L. Richards, The Aminocarbyne Ligand CNH2 Metal-centred Synthesis from a Cyanosilane, Preparation and X-Ray... 

Carbon-Carbon Bond Formation with Cyanosilanes... 

Jacobsen et al. have reported that peptide Schiff bases and an Al-salen complex are valuable for asymmetric hydrocyanation of imines with TBSCN [660] and TMSCN [661], respectively. It is, however, most likely that HCN arising from these cyanosilanes and adventitious water is the reactive nucleophile. Hoveyda et al. also have used TMSCN as a source of HCN in the hydrocyanation of imines catalyzed by a Ti-peptide Schiff base complex [662],... 

The Ni-catalyzed reaction of 2-bromo-l,6-heptadienes with cyanosilanes affords cyclic and open chain adducts (Scheme 10.245) [669]. TMSCN and El.SiCN are available for this reaction whereas bulky cyanosilanes such as TBSCN and i-PtsSiCN result in sluggish or incomplete reactions leading to predominant formation of fhe open chain adducts. The product ratio is strongly affected by the substitution pattern of fhe substrate. 

Pseudohalide Derivatives of Silicon and Tin.—Dimethyl cyanosilane, Me2Si(CN)H, has been examined by i.r., Raman, and microwave spectroscopy, from which precise structural parameters and the dipole moment have been determined. From the low-frequency vibrational assignment, an upper limit of 2.8kcalmor for the barrier to internal rotation of the methyl groups was deduced. Trimethylcyanosilane forms 1 1 adducts of composition (63) with... 

Quite common too is the treatment of alkyl- or arylhalogenosilanes with silver cyanide to synthesize the corresponding cyanosilanes (equation 252)269. Finally, 521 can also be... 

Near total 1,2- and 1, 3-asymmetric induction was observed in reactions of a- and -alkoxyacyl cyanides respectively, with the tertiary cyanohydrins to obtained being configurationally stable. Secondary cyanohydrins were obtained after addition of cyanosilanes to the acyl cyanides under similar conditions but with only partial asymmetric induction. The potential application of these methods to the synthesis of carbohydrates was noted. 

Numerous silicon organic compounds are efficiently and simply prepared using PTC methodology. Thus the most convenient and economical way of synthesis of trimethyl cyanosilane and other trialkylcyanosilanes, important reagents in organic chemistry, consists in use of liquid-solid PTC (eq. 184). 

The aminocarbyne ligand CNH2 Metal-centred synthesis from a cyanosilane, preparation and X-ray structure of trans- [ReCl (CNH2) (Ph2PCH2CH2PPh2) 2] BF4 J.C.S. Chem.Commun., (1986), 246-247... 

Cyclohexanone allowed to react with an equimolar amount of trimethylsilyl cyanide in the presence of a trace of zinc iodide product. Y 94%. - The 0X0 compds. may be readily regenerated in dil. aq. acid or base. F. e., also from aldehydes, s. D. A. Evans, L. K. Truesdale, and G. L. Carroll, Chem. Commun. 1973, 55 with AlClg cf. W. Lidy and W. Sundermeyer, B. 106, 587 (1973) f. reactions with cyanosilanes cf. Tetrah. Let. 1973, 1449 preferential protection of carbonyl groups in quinones, f. catalysts, cf. Am. Soc. 95, 5822 (1973). 

Reactions with cyanosilanes a-Siloxynitriles from oxo compds. 

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