METALATION OF PYRAZINETHIOCARBOXAMIDES METALATION OF DIAZINES XXVI

摘要

Some new pyrazinethiocarboxamides were synthesized and metalated with LTMP in tetrahydrofuran.The reaction of these lithio derivatives with various electrophiles gave access to a large range of 2,5-disubstituted pyrazines.This unexpected regioselectivity was established by application of gradient enhanced HMBC sequence for the observation of long range ~1H-~15N heteronuclear couplings at natural abundance.