# Atroposelective Formal [2 + 5] Macrocyclization Synthesis for a Novel All-Hydrocarbon Cyclo[7] Meta-Benzene Macrocycle

## TL;DR

Scientists synthesized a new all-hydrocarbon macrocycle with axial chirality and studied its unique structural and racemization properties.

## Contribution

The paper introduces a novel atroposelective synthesis method for an all-hydrocarbon cyclo[7] meta-benzene macrocycle.

## Key findings

- CDMB-7 has an irregular bowl-like shape with C2 symmetry and two diastereoisomers.
- Its racemization occurs spontaneously at room temperature within 30 minutes.
- The macrocycle's conformational isomers remain stable at high temperatures (393 K).

## Abstract

A novel axially chiral all-hydrocarbon cyclo[7] (1,3-(4,6-dimethyl)benzene (CDMB-7) was designed and synthesized using atroposelective[2 + 5] cyclization through Suzuki–Miyaura coupling. CDMB-7 adopts an irregular bowl-like shape with C2 symmetry and exhibits two diastereoisomers in its crystallographic structure. The conformational isomers of CDMB-7 racemates remain stable at high temperatures (393 K). High-performance liquid chromatography (HPLC) confirmed that a single chiral isomer will spontaneously undergo racemization within 30 min at room temperature. This finding opens up possibilities for achieving adaptive chirality in all-hydrocarbon cyclo[7] m-benzene macrocycles.