Continuous-Flow Synthesis of Cycloparaphenylene Building Blocks on a Large Scale.

The synthesis of [n]cycloparaphenylenes ([n]CPPs) and similar nanohoops is usually based on combining building blocks to a macrocyclic precursor, which is then aromatized in the final step. Access to those building blocks in large amounts will simplify the synthesis and studies of CPPs as novel functional materials for applications. Herein, we report a continuous-flow synthesis of key CPP building blocks by using versatile synthesis techniques such as electrochemical oxidation, lithiations and Suzuki cross-couplings in self-built reactors on up-to kilogram scale.

Alkylphosphinites as Synthons for Stabilized Carbocations.

We present a new acid-free method for the generation of carbocations based on a redox condensation reaction that enables SN1 reactions with a variety of nucleophiles. We utilize readily synthesized phosphinites that are activated by diisopropyl azodicarboxylate to form betaine structures that collapse upon adding a pronucleophile, thereby yielding reactive carbocation intermediates. We also employ this approach for the alkylation of some bioactive molecules.