Co-cyclizations of nitrogen-containing acetylenes induced by a nickel triphenylphosphine complex to give aminoindane, isoindoline and isoindolinone derivatives

Abstract

N-Methyl-, N,N-dimethyl-, N,N-diethylprop-2-ynylamines, N-prop-2-ynylacetamide and N-prop-2-ynylbenzamide are co-cyclized with diethyl hepta-1,6-diyne-4,4-dicarboxylate at room temperature in the presence of stoichiometric nickel(0) to give amino- and amido-indanes in fair to good yields. The structure of the product from N-prop-2-ynylbenzamide was established by X-ray crystallography. Likewise, N-alkyldiprop-2-ynylamines co-cyclize with methyl prop-2-ynyl ether to give isoindolines albeit in lower yields; the corresponding reaction of short chain N-alkynylalkynamides requires heating to 60 °C but gives isoindolinones and a 1,4-dihydroisoquinolin-3(2H)-one as mixtures of regioisomers in good yields. Attempts to synthesize medium-ring, benzo-fused lactams by this method failed.