Intramolecular Hydrogen Bonding of 5-Acyl-3-methylrhodanines

A series of 5-acyl-3-methylrhodanines have been synthesized. The structures of those are described using H-1 and C-13 NMR, deuterium isotope effects on C-13 chemical shifts and DFT, calculations. The compounds exist as exocyclic enols with intramolecular hydrogen bonds to the C = ONCH3 oxygen. No signs of enhanced mesoionic character were found.