Thermally stable monosubstituted thiophene 1-oxide and 1-imides stabilized by a bulky rind group at their 3-position: Synthesis, structure, and inversion barriers on the sulfur atom

The synthesis and characterization of thermally stable monosubstituted thiophene 1-oxide and 1-imides stabilized by EMind (1,1,7,7-tetraethyl-3,3,5,5-tetramethyl-s-hydrindacen-4-yl) group on the 3-position are described. In addition to the molecular structures determined by X-ray crystallography, inversion barriers at the three-coordinated sulfur atoms have been determined by a coalescence method using diastereotopic C-3 and C-5 indacene carbon atoms as a ¹³CNMR probe.