Preparation of polycyclic azaarenes by an extended Pomeranz-Fritsch procedure

Article abstract of DOI:10.1055/s-2007-983744

An extension of the Pomeranz-Fritsch procedure has been evaluated as a route to some polycyclic azaarenes. Aromatic aldehydes were treated with the dimethyl and diethyl acetals of 2-aminoethanal, the resulting imines reduced to amines which were tosylated and the resulting sulfonamides treated under a range of acidic conditions. The two naphthaldehydes led to benzo[f]isoquinoline and benzo[h]isoquinoline in overall yields of 13% and 36%. Phenanthrene-9- carbaldehyde and phenanthrene-3-carbaldehyde gave dibenzo[f,h]isoquinoline and naphtho[2,1-g]isoquinoline, respectively, as the major tetracyclic products. No pentacyclic product was obtained from a similar sequence starting from pyrene-1-carbaldehyde. Georg Thieme Verlag Stuttgart.