An efficient one-pot protocol for the synthesis of isoquinolinium-2-yl
amides starting from readily available hydrazides and 2-alkynylbenzaldehydes
is described. The key step of the protocol is a silver(I)-catalyzed
ring-closure of N′-(2-alkynylbenzylidene)hydrazides
that are generated in situ. Isoquinolinium-2-yl amides derived from tert-butoxycarbonyl hydrazide could be
further deprotected, delivering 2-aminoisoquinolinium trifluoroacetates.
alkynes - hydrazides - isoquinolines - annulation - ylides - silver catalysis