Reaktionen von (−)-Ephedrin bzw. (+)-Norpseudoephedrin und Derivaten mit N,N-Dimethylacetamid-dimethylacetal und N,N,-Dimethylformamid-dimethylacetal.

The reactivity of (−)-ephedrine ( 2) and (+)-norpseudoephedrine ( 3) towards the amidacetals 1 a/b has been studied. Both 2 and 3 were acetylated resp. formylated at first at the amino group. Nevertheless, derivatives of 2 and 3 possessing a trisubstituted amino group react with 1 a in a [3.3] sigmatopic rearrangement to ortho substituted dimethylcarbamoylmethyl derivatives. By subsequent reduction with lithiumaluminiumhydride the aromatic compounds 8, 13, and 18 with two aminoethyl groups are easily available. In contrast to these results 1 b did not furnish any rearrangement products. [ABSTRACT FROM AUTHOR]