USE OF POLYPHOSPHORIC ACID IN POMERANZ-FRITSCH SYNTHESIS OF ISOQUINOLINES

A number of 7,8 and 1-substituted isoquinolines have been synthesized by the Pomeranz-Fritsch procedure using polyphosphoric acid as cyclizing agent. Though giving only moderate yields the method was successful in all cases, particularly for the preparation of 8-substituted isoquinolines, which in most cases are unobtainable from cyclization using sulphuric acid. In addition, the 12H-[1]-benzoxepino[2.3.4-ij]isoquinoline system, present in the cularine alkaloids, has been elaborated. © 1969.