Syntheses of 1-substituted isoquinoline and 1,4-benzoxazepine derivatives by pomeranz-fritsch reaction (studies on the syntheses of heterocyclic compounds. CCCXX

Abstract

Since the compound (VI) has been well known as a peripheral vasodilator agent, synthesis of its benz [e] [1, 4] oxazepine derivatives was carried out in order to examine their activities. Furthermore, 1-benzylisoquinoline derivatives as well as 1, 4-benzoxazepine derivatives had not yet been obtained by Pomeranz-Fritsch reaction with sulfuric acid as condensing reagent. We now have established that 1-benzylisoquinolines (XXV, XXVI, XXVII and XXVIII) as by-products and benz [e] [1, 4] oxazepine derivatives (XXIX, XXX, XXXI and XXXII) can be obtained by Pomeranz-Fritsch reaction with polyphosphoric acid. In addition, cyclization of XXXIV with polyphosphoric acid gave debrominated 1-benzylisoquinoline (II) together with 1, 4-benzoxazepine derivative (XXXV). Although cyclization of XXXVI and XXXVII afforded 1-benzylisoquinoline derivatives (XXXVIII and XL), the expected 1, 4-benzoxazepine derivatives (XLI and XLII) were not obtained in both cases.