Synthesis of Condensed Heterocycles by the Gould–Jacobs Reaction in a Novel Three-Mode Pyrolysis Reactor

In the present paper we report the synthesis of condensed pyrimidone heterocycles (including novel ones) prepared by the Gould–Jacobs reaction using an in-house-built vacuum-to-high pressure multipurpose “three-mode” pyrolysis reactor. Four of the ring systems have not been described in the literature to date. The pyrolysis reactor has (i) a flash vacuum pyrolysis (FVP) module that applies high vacuum (10–3 mbar), letting the starting material through the reactor chamber heated up to 1000 °C; (ii) a pneumatic spray pyrolysis (PSP) module that can inject nonvolatile reactants to the heated reactor zone; and (iii) a high-pressure pyrolysis (HPP) continuous-flow module that operates from atmospheric to 400 bar pressure and between room temperature and 600 °C. The capabilities of the pyrolysis reactor were demonstrated by comparison experiments on two different condensed pyrimidone bicyclic ring systems, and the established reaction conditions were then successfully applied to the synthesis of another six con...