Synthesis method null of benzo furans

摘要

PURPOSE:To obtain the titled compound useful as a synthetic intermediate for antibiotics under a mild condition by easy operation and in high yield, by using a trityl salt as a catalyst and reacting a readily obtainable silyl enol ether with a para-benzoquinone as raw materials. CONSTITUTION:A silyl enol ether shown by formula I (R1-R3 are alkyl, aryl, alkenyl or alkynyl and preferably 1-10C) is reacted with a para-benzoquinone shown by formula II [X2 is O or sulfonamide NR5 (R5 is sulfonyl); R4 is H, halogen, alkyl (preferably 1-6C alkyl), alkenyl or alkynyl] or a quinonimide in the presence of a catalytic amount of a trityl salt such as TrClO4 shown by the formula TrX (X is metallic salt or solvent such as methylene chloride at -100 deg.C- room temperature to give the aimed compound shown by formula III or formula IV (X1 is OH or NH-R5).