3D printing has the potential to transform the way in which chemical reactions are carried out due to its low‐cost, ease‐of‐use as a technology and its capacity to expedite the development of iteratively enhanced prototypes. In this present study, we developed a novel, low‐cost polypropylene (PP) column reactor that was incorporated into an existing continuous‐flow reactor for the synthesis of heterocycles. The utility and solvent resistance of the printed devices were explored in S_NAr reactions to produce substituted aniline derivatives and in the synthesis of bicyclic and tetracyclic heterocycles. Using this approach, a range of heterocyclic compounds was synthesised including the core structure of the natural product (±)‐γ‐lycorane and structurally complex compounds based on the tetracyclic core of the erythrina alkaloids.

An efficient acetic acid catalysed reaction has been developed for the synthesis of 4-aryl substituted pyrrolo[1,2-a]quinoxalines from readily available starting materials. A range of structures have been synthesised in very good to excellent yields. The one-pot reaction proceeds through imine formation, cyclisation followed by air oxidation.

Acyclic bissulfonylnitroxides have never been isolated, and degrade through fragmentation. In an approach to stabilising a bissulfonylnitroxide radical, the cyclic, peri-substituted N,N-bissulfonylhydroxylamine, 2-hydroxynaphtho[1,8-de][1,3,2]dithiazine 1,1,3,3-tetraoxide (1), has been prepared by formal nitrogen insertion into the sulfur–sulfur bond of a sulfinylsulfone, naphtho[1,8-cd][1,2]dithiole 1,1,2-trioxide. The heterocyclic ring of 1 is shown to adopt a sofa conformation by X-ray crystallography, with a pseudo-axial hydroxyl group. N,N-Bissulfonylhydroxylamine 1 displays high thermal, photochemical and hydrolytic stability compared to acyclic systems. EPR analysis reveals formation of the corresponding bissulfonylnitroxide 2 upon oxidation of 1 with the Ce(IV) salts CAN and CTAN. Although 2 does not undergo fragmentation, it cannot be isolated, since hydrogen atom abstraction to reform 1 occurs in situ. The stability and reactivity of 1 and 2 are compared with the known cyclic benzo-fused N,N-bissulfonylhydroxylamine, N-hydroxy-O-benzenedisulfonimide (6), for which the X-ray data, and EPR of the corresponding nitroxide 10, are also reported for the first time.