公开(公告)号：DE2934252A1

公开(公告)日：1981-03-12

申请号：DE2934252

申请日：1979-08-24

Applicant: BASF AG

Inventor： HARTWIG WOLFGANG DR ,  SCHOELLKOPF ULRICH PROF DR

IPC: C07D213/55 ,  C07D215/12 ,  C07D241/08 ,  C07C101/18

Abstract: New processes are claimed for the prodn. of pure or substantially pure optically active alpha-aminoacid derivs. of the formulae Me-C(R1)(NH2)-COOR' (Ia) and R1-CH(NH2)-COOR' (Ib) in which R1 is a non-aromatic organic residue and R' is H or 1-4C alkyl. The first step in the prodn. of (Ia) comprises self-condensation of pure or substantially pure optically active alpha-alanine or its 1-4C alkyl ester to give (R,R)-3,6-dimethyl piperazine-2,5-dione (IIIa) or (S,S)-3,6-dimethylpiperazine-2, 5-dione (IIIb). The first step in the prodn. of (Ib) comprises reaction of glycine or a glycine 1-4C alkyl ester with a pure or substantially pure optically active alpha-methyl-phenylalanine deriv. of the formula Me-C(R2)(NH2)-COOR' (IIc) (where R2 is benzyl opt. substd. in the phenyl residue) to give a 3R- or 3S-3-methyl-3-R2-piperazine-2, 5-dione (IIIc) or (IIId); alternatively, (IIIc) or (IIId) may be prepd.via the corresponding open chain dipeptides by conventional methods. Subsequently, (IIIa)-(IIId) are reacted with an alkylating agent to give a corresponding 2,5-di(1,4-C alkoxy)-3,6-dihydropyrazine deriv.(IVa-d). This is reacted at least an equivalent amount of a strongly basic organometallic cpd. to give a deriv. of (IVa-d) monosubstd. in the 6-position by the metal of the organometallic cpd., and the metal deriv. is reacted with a cpd. R1-Y(V) (where Y is a residue which can be split off as an anion). The resulting deriv. of (IVa-d) substd. in the 6-position by R1 is hydrolysed by means of an acid, and (Ia) or (Ib) is isolated from the hydrolysis mixture by conventional methods. Also claimed are corresponding 2,5-dialkoxy-3,6-dihydro-pyrazine derivs.