p-Toluenesulfonyl Cyanide

(R = p-tolyl)

[19158-51-1]  · C8H7NO2S  · p-Toluenesulfonyl Cyanide  · (MW 181.23) (R = methyl)

[24225-08-9]  · C2H3NO2S  · Methanesulfonyl Cyanide  · (MW 105.13) (R = phenyl)

[24224-99-5]  · C7H5NO2S  · Benzenesulfonyl Cyanide  · (MW 167.20)

(nitrile group as dienophile in [4 + 2] cycloadditions; nitrile group as source of +CN and &bdot;CN)

Alternate Name: tosyl cyanide

Physical Data: R = p-tolyl, mp 49-50 °C. R = methyl, bp 68-69 °C/15 mmHg. R = phenyl, bp 73 °C/0.1 mmHg.

Form Supplied in: tosyl cyanide is available as an off-white solid.

Preparative Methods: sulfonyl cyanides are best prepared by the reaction of cyanogen chloride with the sodium salt of a sulfinic acid. Procedures for tosyl cyanide1 and methanesulfonyl cyanide2 have been published.

Handling, Storage, and Precautions: tosyl cyanide has been reported to undergo occasionally violent decomposition on drying.1 Methanesulfonyl cyanide can be stored in a well-stoppered bottle, at or below 0 °C, over a prolonged period without loss of purity and can be distilled without decomposition.2 Use in a fume hood.

Cycloadditions.

In contrast to the situation with most nitriles, the cyano group of sulfonyl cyanides can function as a dienophile in [4 + 2] cycloadditions under relatively mild conditions. Reaction of cyclopentadiene with either tosyl1 or methanesulfonyl3 cyanide leads, after hydrolysis of the intermediate formed, to 2-azabicyclo[2.2.1]hept-5-en-3-one (1) (eq 1), a useful intermediate for the preparation of carbanucleosides.

The reaction of tosyl cyanide with 2-aza-1,3-dienes has been used to prepare pyrimidines (eq 2);4 Trichloroacetonitrile showed comparable reactivity in this reaction. The regioselective cycloaddition of tosyl cyanide with 1-alkoxy-1,3-dienes has been used for the preparation of 2-arylsulfonylpyridines.5

Cycloadditions with 1,3-dipoles are also known: tosyl cyanide reacts with diazomethane to give 4-tosyl-1,2,3-triazole (68% yield) and with benzonitrile N-oxide to give 3-phenyl-5-tosyl-1,2,4-oxadiazole (78% yield).6

Reactions with Nucleophiles.

Tosyl cyanide acts as an electrophilic cyanating agent in reactions with many nucleophiles including phenoxides, Grignard reagents, amines, and thiols.7 Tosyl cyanide proved to be a much more effective reagent for the cyanations of ketone enolates than either Cyanogen Bromide or phenyl cyanate, although the yields were low with methyl ketones.8 Reaction of vinylcuprates with tosyl cyanide provided a stereospecific synthesis of 2-alkenenitriles (yields >90%), although cyanogen chloride could also be used.9 A convenient synthesis of 2-cyanoimidazoles using either tosyl cyanide or phenyl cyanate has been reported (eq 3).10

A magnesium complex of the cyanobisoxazoline (2), prepared in high yield (>70%) using PhSO2CN (eq 4), was useful as a catalyst for the enantioselective conversion of aldehydes to cyanohydrins using Cyanotrimethylsilane.11

Both tosyl and methanesulfonyl cyanide react with alcohols in the presence of 1,8-Diazabicyclo[5.4.0]undec-7-ene or 1,4-Diazabicyclo[2.2.2]octane at or below rt to give sulfinate esters. A mechanism involving the intermediacy of sulfinyl cyanates was proposed (eq 5).12

Isolable adducts can be obtained from the reaction of sulfonyl cyanides with a-nucleophiles. Reaction of tosyl cyanide with phenylhydrazine gave (3), which was reacted further with Triethyl Orthoformate to the triazole (4) (eq 6).13 Similarly, hydroxylamine reacts with arylsulfonyl cyanides to give isolable arylsulfonyl formamidoximes (63-87%), which were converted to 5-amino-3-arylsulfonyl-1,2,4-oxadiazoles.14

Radical Reactions.

The photochemical (UV irradiation)15 and thermal (Azobisisobutyronitrile catalyzed)16 addition of sulfonyl cyanides to alkenes has been described (eq 7). The photochemical reaction was reported not to function with alkynes; however, AIBN-catalyzed thermal addition of tosyl cyanide to 1-hexyne gave (5) as a mixture of geometrical isomers (eq 8).16 The AIBN-catalyzed reaction of sulfonyl cyanides with 1,3-dienes gave products of 1,4-addition.16

The reaction of sulfonyl cyanides with carbon radicals generated by visible irradiation of (6) gave nitriles in good yields (eq 9).17

Related Reagents.

Chlorosulfonyl Isocyanate; Cyanogen Bromide; Trichloroacetonitrile.


1. Daluge, S.; Vince, R. JOC 1978, 43, 2311.
2. Vrijland, M. S. A. OS 1977, 57, 88.
3. Griffiths, G.; Previdoli, F. Eur. Patent 508 352, 1993 (CA 1993, 118, 59 591).
4. Bayard, Ph.; Sainte, F.; Beaudegnies, R.; Ghosez, L. TL 1988, 29, 3799.
5. Rüffer, U.; Breitmaier, E. S 1989, 623.
6. Van Leusen, A. M.; Jagt, J. C. TL 1970, 971.
7. Van Leusen, A. M.; Jagt, J. C. TL 1970, 967.
8. Kahne, D.; Collum, D. B. TL 1981, 22, 5011.
9. Westmijze, H.; Vermeer, P. S 1977, 784.
10. Dudfield, P. J.; Ekwuru, C. T.; Hamilton, K.; Osbourn, C. E.; Simpson, D. J. SL 1990, 277.
11. Corey, E. J.; Wang, Z. TL 1993, 34, 4001.
12. Barton, D. H. R.; Jaszberenyi, J. Cs.; Theodorakis, E. A. T 1991, 47, 9167.
13. Van Leusen, A. M.; Jagt, J. C. RTC 1975, 94, 12.
14. Treuner, U. S 1972, 559.
15. Pews, R. G.; Evans, T. E. CC 1971, 1397.
16. Fang, J.-M.; Chen, M.-Y. TL 1987, 28, 2853.
17. Barton, D. H. R.; Jaszberenyi, J. Cs.; Theodorakis, E. A. T 1992, 48, 2613.

Gareth J. Griffiths

Lonza, Visp, Switzerland



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