A NEW SYNTHESIS OF FUNGICIDAL METHYL (E)-3-METHOXYPROPENOATES

Several structural analogues of strobilurin A having general formula ( E)-18, in which the methyl (E)-3-methoxypropenoate unit is linked to s ubstituted aromatic, alkenyl or cyclopentenyl substrates, have been ef ficiently and selectively prepared by Pd-catalyzed cross-coupling reac tions between (Z)-2-methoxy-1-(methoxycarbonyl)ethenylzinc halides, (Z )-19, and aryl halides, alkenyl halides or triflates or cyclopentenyl triflates, respectively. Compounds (Z)-19, which represent a new class of highly functionalized and stereodefined organozinc derivatives, ha ve been synthesized in very high yield by reaction of THF solutions of easily available methyl (Z)-2-iodo- or (Z)-2-bromo-3-methoxypropenoat e, (Z)-8 and (Z)-12, respectively, with an activated Zn/Ag couple in t he presence of TMEDA. Compounds (E)-18 synthesized according to this p rocedure include substances which are known to be able to control agro chemically important fungi as well as derivatives which are able to in hibit the growth of fungi which deteriorate papery materials. (C) 1998 Elsevier Science Ltd. All rights reserved.