METHODS FOR PREPARING TETRASUBSTITUED PYRAZINES IN WATER UNDER MILD CONDITION BY USING BAKER'S YEAST

摘要

PURPOSE: Methods for preparing tetrasubstitued pyrazines using baker's yeast are provided, thereby easily and environment-friendly preparing tetrasubstitued pyrazines in water under mild condition. CONSTITUTION: The method for preparing tetrasubstitued pyrazines of formula (2) using baker's yeast comprises the steps of: (1) preparing a solution of baker's yeast; and (2) dissolving beta-keto alpha-oxime carbonyl derivatives of formula (1) in hydrophilic organic solvent and adding the solution into the baker's yeast solution to carry out chemoselective microbial reduction, wherein R1 is methyl, ethyl or phenyl; R2 is hydrogen, methyl or benzyl; R3 is methoxy, ethoxy, benzyloxy or phenylamine; the organic solvent is selected from benzene, toluene and hexane.