Preparation of Heterocyclic Fluorine Compounds by the Schiemann Reaction. III. Some Monofluoroisoquinolines.

摘要

The preparation of some fluoroisoquinolines was undertaken as part of a continuing study of the preparation and properties of heterocyclic fluorine compounds. The synthesis of 1-, 3-, 4-, and 5- fluoroisoquinoline and the attempted synthesis of 6-fluoroisoquinoline is reported in this paper. The diazonium fluoborates, intermediates in the Schiemann reaction, are usually stable enough to be isolated, and are thermally decomposed to give the corresponding fluorine compounds. Many of the heterocyclic diazonium fluoborates, however, are not stable enough to be isolated, although they do decompose to form heterocyclic fluorine compounds; thus all three of the pyridinediazonium fluoroborates and 2- and 4-quinolinediazomurn fluoborate decompose at room temperature or below. In contrast, the stability of 3-quinoline- diazonium fluoborate (m.p. 95 deg) is noteworthy; it resembles in this respect the 5-, 6-, 7- and 8-quinolinediazonium fluoborates, all of which are relatively stable. jg p.2.