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The development of efficient methods for the synthesis of substituted polycyclic arenes with various topologies is in high demand due to their excellent electrical and optical properties. In this work, a series of gem-dimethylcyclopentane-fused arenes with more than ten topologies were synthesized via a 1,5,7-Triazabicyclo[4.4.0]­dec-5-ene (TBD)-mediated dehydro-Diels–Alder reaction with moderate to good yields. The introduction of the near-planar gem-dimethylcyclopentane moiety not only impacts the molecular conjugative system but also regulates the intermolecular π–π interactions and crystal packing, which are critical for the photoelectric performance of arenes. The photophysical properties, molecular geometry, molecular packing of these compounds, and electrochemical properties were investigated by UV–vis absorption, fluorescence emission spectra, DFT calculations, single-crystal X-ray structure analysis, and cyclic voltammetry study.

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Synthetic methods of unnatural α-amino acids have always been the focus of extensive research due to their significant bioactivities. However, convenient transition-metal-free catalyzed methods are still in demand. Herein, we report a novel strategy for the construction of an unnatural α-amino acid skeleton via intramolecular rearrangement of carbamates, which are readily available from amines and their common protecting groups. This rearrangement could afford a variety of amino ester products in up to 98% yield, even in gram-scale reaction. The reaction mechanism was studied in detail through experiments and theoretical calculations. The complex-induced proximity effect (CIPE) from the 2-pyridyl group is shown to be indispensable for this transformation.