Schönenberger, Helmut and Fuchsberger, K. D. and Brinkmann, Rolf (1967) Separation of the organic bases by Craig partition. VII. Acyl migration in the stereoisomeric N-(N,N-dimethylphenylalanyl)ephedrines. Archiv der Pharmazie und Berichte der Deutschen Pharmazeutischen Gesellschaft 300 (2), pp. 126-135.
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cf. CA 66: 49281u. The compds. studied were N-(L-N,N-dimethylphenylalanyl)-L-ephedrine (I), N-(D-N,N-dimethylphenylalanyl)-L-ephedrine (II), N-(L-N,N-dimethylphenylalanyl)-L-pseudoephedrine (III), and N-(D-N,N-dimethylphenylalanyl)-L-pseudoephedrine (IV). In every case, only the ester of L-pseudoephedrine resulted, even under mild conditions (room temp., acetone-HCl). Complete inversion of the erythro derivs. occurred. In 2N HCl at 80 Deg, the ester from I formed quant. in 10 min. while that from III (retention of configuration) required 25 hrs. With II, 5 hrs. and with IV, 22 hrs. were required. The 4 amides pass through either of 2 cyclic intermediates during the migration, L,L-(V) or D,L-pseudooxazolidine (VI). The rates are explained by steric considerations of the mechanism, V resulting from I via inversion and from III with retention, and VI, from II via inversion and IV with retention. Craig partition as described previously (loc. cit.) was used to sep. and det. the reaction products. Twenty-four partition steps using a solvent mixt. of 0.5M citrate buffer (pH 4/5)-MeOH-CHCl3 (9:1:10 parts by vol.) were required for sepn. into N- and O-aminoacylephedrines. The O-(L-N,N-dimethylphenylalanyl)-L-pseudoephedrine m. 170-2 Deg, [alpha ]20D + 114 Deg (c = 0.0055 g./ml., 5N HCl) and the O-(D-N,N-dimethyl-) ester melts at 174-6 Deg, [alpha ]20D 48 Deg (c 0.0055 g./ml., 5N HCl).
|Additional information (public):||CAN 67:2830 25 Noncondensed Aromatic Compounds 2480-20-8; 2673-32-7; 5042-94-4; 7275-84-5 Role: RCT (Reactant), RACT (Reactant or reagent) (acyl group migration in); 14355-01-2P; 14355-02-3P Role: SPN (Synthetic preparation), PREP (Preparation) (prepn. of)|
|Institutions:||Chemistry and Pharmacy > Institute of Pharmacy > Retired Professors > Prof. Schönenberger|
|Keywords:||Acyl groups (migration of, in alpha -(dimethylamino)-N-(beta -hydroxy-alpha -methylphenethyl)-N-methylhydrocinnamamide) EPHEDRINE STEREOISOMERISM STEREOISOMERISM EPHEDRINE PSEUDOEPHEDRINE STEREOISOMERISM|
|Subjects:||500 Science > 540 Chemistry & allied sciences|
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Unknown|
|Deposited On:||19 Nov 2010 09:20|
|Last Modified:||19 Nov 2010 09:20|