Regioselective ring opening of amino epoxides with nitriles: an easy synthesis of (2R,3S)- and (2S,3S)-1,3-diaminoalkan-2-ols with differently protected amine functions.

ABSTRACT

[reaction see text] Transformation of enantiopure (2R,1'S)- or (2S,1'S)-2-(1-aminoalkyl)epoxides 1 or 2 into the corresponding (2R,3S)- and (2S,3S)-1,3-diaminoalkan-2-ols 3 or 4 is described. The opening of the epoxide ring with different nitriles (Ritter reaction) takes place with total selectivity and in high yields in the presence of BF3.Et2O. Interestingly, the two amine groups are differently protected. A mechanism to explain this transformation is proposed.