Reduction of β-enamino ketones 1 with NaBH(OAc)3 in glacial acetic acid gave β-amino ketones 3 in 65% to 67% yield. These data and others observed in the reduction of β-enamino ketones 1 to preferentially syn γ-amino alcohols 2 with NaBH4/HOAc suggest that in this last reaction we have firstly the reduction of the β-enamino ketones 1 to produce the β-amino ketones 3, and then this compound is reduced to the γ-amino alcohols 2. We can say from this results that the diastereosselectivity of the reduction of β-enamino ketones 1 to mainly syn γ-amino álcohols 2, can be analysed as a competition between a chair-like transition state and a boat-like transition state, obtained from the β-amino ketones 3. © 2006 Sociedade Brasileira de Química.17714401442Harris, M.I.N.C., Braga, A.C.H., (2004) J. Braz. Chem. Soc., 15, p. 971Harris, M.I.N.C., (1993), Ph.D. Thesis, Universidade Estadual de Campinas, BrazilBraga, A. C. H.Harris, M. I. N. C.Br PI 9.502.467-0, 1995. (CA 128:243740)Gribble, G.W., Nutaitis, C.F., (1985) Org. Prep. Proced. Int., 17, p. 317Gribble, G.W., (1998) Chem. Soc. Rev., 27, p. 395For a better understanding of this reactivity, theoretical studies are in progressnoteMarchini, P., Liso, G., Reho, A., (1975) J. Org. Chem., 40, p. 3453Evans, D.A., Chapman, K.T., Carreira, E.M., (1988) J. Am. Chem. Soc., 110, p. 3560Palmieri, G., Cimarelli, C., (2006) Arkivoc, p. 104