1. Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (UK);2. School of Chemistry, University of Southampton, University Road, Southampton, SO17 1BJ (UK)
Abstract:
A comparative study using NMR spectroscopy and designed top‐pan molecular balances demonstrates that the noncovalent interaction of a hydroxy group with π‐deficient pyrazine and quinoxaline units involves a lone pair–heteroarene interaction which is much stronger and solvent independent when measured relative to the classical π‐facial hydrogen bond to a benzene ring. Alkyl fluorides also prefer the heteroarene rings over the benzene ring. The attractive interaction between a quinoxaline and a terminal alkyne is also stronger than the intramolecular hydrogen bond to an arene.