2-AMINO-3-CHLOROMETHYL-5-(DICHLOROMETHYL)-PYRAZINES AND PROCESS FOR THEIR PREPARATION

摘要

2-Amino-3,5-di-(halomethyl)-pyrazines of the general formula I (I) where X is either chlorine or bromine, m and n may each be 0, 1, 2 or 3 and R1 and R2 are each hydrogen or a protective group or may furthermore be bonded to one another, in particular those compounds of the formula I in which m is 1 and n is 2 and/or R1 and R2 together form a phthaloyl radical, are useful intermediates for the pteridine building block of folic acid or folic acid analogs. They are obtained by a method in which a 2-amino-3,5-dimethylpyrazine of the general formula II (II) is treated with a chlorinating or brominating agent and, where R1 and/or R2 are protective groups, these are, if desired, eliminated when the chlorination or bromination is complete.