(R = Ph)

[41804-90-4]  · C8H7F3N2O3S  · N-Trifluoromethanesulfonyl-N-phenacylhydrazine  · (MW 268.24) (R = t-BuO)

[56572-25-9]  · C6H11F3N2O4S  · N-Trifluoromethanesulfonyl-N-t-butoxycarbonylhydrazine  · (MW 264.26)

(conversion of alkyl halides to hydrazones of aldehydes and ketones)1

Alternate Name: N-triflyl-N-phenacylhydrazine.

Physical Data: R = Ph, mp 156-158 °C. R = t-BuO, mp 92-94 °C.

Solubility: insol H2O; sol common organic solvents.

Preparative Methods: triflation of the commercial acylhydrazines with Trifluoromethanesulfonic Anhydride and Triethylamine in CH2Cl2.

Handling, Storage, and Precautions: both are stable solids with no known toxicity, but the t-butyl derivative may decompose on long standing at rt and decomposes on mild heating.

General Discussion.

Designed to afford protected derivatives of sensitive aldehydes or ketones directly from the corresponding alkyl halides, these reagents fulfill this function as shown in eq 1. Owing to the various mild methods available for deprotecting hydrazones,2 they serve as useful protection derivatives. Triflamide anions are excellent nucleophiles for displacement reactions of primary and activated secondary halides (or sulfonates) in MeCN, and the added base (Potassium Carbonate) eliminates triflinate ion to form the hydrazones. The N-acyl group is necessary to activate the elimination, which does not occur in its absence. In the case of the t-butoxy derivative, the unsubstituted hydrazone may be recovered with acid as with other t-BOC amine derivatives. This also makes possible the synthesis of unsymmetrical azines, R2C=N-N=CR2.

1. Hendrickson, J. B.; Sternbach, D. D. JOC 1975, 40, 3450.
2. McOmie, J. F. W. Protective Groups in Organic Chemistry; Plenum: New York, 1973, p. 340. Greene, T. W. Protective Groups in Organic Synthesis, 2nd ed.; Wiley: New York, 1991.

James B. Hendrickson

Brandeis University, Waltham, MA, USA

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