Sodium Trifluoroacetoxyborohydride1


[61666-40-8]  · C2H3BF3NaO2  · Sodium Trifluoroacetoxyborohydride  · (MW 149.85)

(a very selective reducing agent for the reduction of nitriles and amides to amines;1 may serve as a source of trifluoroacetaldehyde or its equivalent2)

Solubility: the reagent is rapidly destroyed by H2O and protic solvents; H2 is liberated. Common cosolvents for the reactions of this reagent are CH2Cl2, THF, toluene, and Et2O.

Form Supplied in: not commercially available.

Preparative Methods: normally prepared in situ by the reaction of the appropriate amount of Trifluoroacetic Acid with Sodium Borohydride.1

Analysis of Reagent Purity: has not been characterized.

Handling, Storage, and Precautions: the preparation of and all reactions involving this reagent should be conducted under an inert atmosphere because H2 may be liberated; this is particularly true when NaBH4 powder is used.

Functional Group Reductions.

The combination of strong acid and hydride donor yields a unique and powerful reagent for the reduction of nitriles and amides to amines. The related though less reactive Sodium Tris(trifluoroacetoxy)borohydride effects the deoxygenation of benzylic alcohols and aryl ketones, the reduction of imines, enamines, oximes, and related double bonds, and the reduction of heterocycles (indoles, pyrroles, and some p-deficient heterocyclic systems). In some of these examples the active reagent may be NaBH3OCOCF3.

Whereas nitriles and amides are unaffected by NaBH(OCOCF3)3 (NaBH4 in excess CF3CO2H), the action of NaBH3OCOCF3 on these functional groups leads to amines3 (eqs 1-7).4-10 Noteworthy is the survival of the 1,2-oxazine carbamate (eq 3),6 the diaryl ketone (eq 4),7 the Boc protecting groups (eq 5),8 and the diaryl carbinol (eq 7).10 Thus NaBH(OCOCF3)3 (in CF3CO2H) reduces diaryl carbinols but not amides, while NaBH3OCOCF3 reduces amides but not diaryl carbinols!

Carboxylic acids can be reduced to primary alcohols with NaBH3OCOCF3.11

1. (a) Gribble, G. W.; Nutaitis, C. F. OPP 1985, 17, 317. (b) Nutaitis, C. F. J. Chem. Educ. 1989, 66, 673.
2. Nutaitis, C. F.; Gribble, G. W. S 1985, 756.
3. (a) Umino, N.; Iwakuma, T.; Itoh, N. TL 1976, 2875. (b) Umino, N.; Iwakuma, T.; Itoh, N. TL 1976, 763.
4. Ishikawa, F.; Saegusa, J.; Inamura, K.; Sakuma, K.; Ashida, S. JMC 1985, 28, 1387.
5. Mayer, J. P.; Cassady, J. M.; Nichols, D. E. H 1990, 31, 1035.
6. Baldwin, J. E.; Otsuka, M.; Wallace, P. M. T 1986, 42, 3097.
7. Oklobdzija, M.; Fajdiga, T.; Kovac, T.; Zonno, F.; Sega, A.; Sunjic, V. Acta Pharm. Jugosl. 1980, 30, 121.
8. Sundaramoorthi, R.; Marazano, C.; Fourrey, J.-L.; Das, B. C. TL 1984, 25, 3191.
9. Nutaitis, C. F. SC 1992, 22, 1081.
10. Sorgi, K. L.; Maryanoff, C. A.; McComsey, D. F.; Graden, D. W.; Maryanoff, B. E. JACS 1990, 112, 3567.
11. Suseela, Y.; Periasamy, M. T 1992, 48, 371.

Gordon W. Gribble

Dartmouth College, Hanover, NH, USA

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