An Easy and Efficient Method to Produce γ-Amino Alcohols by Reduction of β-Enamino Ketones

The synthesis of γ-amino alcohols 1 is of great interest due to the pharmacology of these compounds and their derivatives. This functionality is found in several antibiotics and other biologically active natural products. Several synthetic methods have been described for the synthesis of γ-amino alcohols 1 from diols, hydroxazols, lactams and lactones, but the more important methods are those where one can obtain γ-amino alcohols 1 by reduction of 1,3-difunctionalized unsaturated compounds containing nitrogen and oxygen, such as β-hydroxy oximes, β-enamino ketones 2, and, more frequently, by the reduction of β-amino ketones. γ-Amino alcohols 1, mainly syn, can be synthesized by reduction of β-enamino ketones 2 with Na in PrOH/ tetrahydrofuran or with CeCl 3 / LiBH 4 /tetrahydrofuran. On the other hand, the combination of NaBH 4 in a carboxylic acid media has yielded an efficient reducing reagent. We wish to report herein a simple and efficient method to produce γ-amino alcohols 1 through the reduction of β-enamino ketones 2 with NaBH 4 in glacial acetic acid, which has been sucessfully used in our laboratory.