A three-component reaction of 2-alkynylbenzaldehydes, a sulfonohydrazide
and dimethyl cyclopropane-1,1-dicarboxylate, co-catalyzed by silver(I)
triflate and nickel(II) perchlorate hexahydrate, is described, which
affords 2,3,4,11b-tetrahydro-1H-pyridazino[6,1-a]isoquinolines in moderate
to good yields. A possible reaction pathway that proceeds via a
tandem 6-endo-cyclization and [3+3] cycloaddition
sequence is proposed.
2-alkynylbenzaldehydes - dimethyl cyclopropane-1,1-dicarboxylate - nickel perchlorate
hexahydrate - silver(I) triflate - sulfonohydrazide