Cleavage of 5-nitro-2-(trimethylsilylmethyl)thiophene by methanolic sodium methoxide. U.v. spectroscopic and solvent isotope effect evidence for generation of the anion [5-O2N·C4H2S· CH2-2]–

Abstract

The reaction of 5-nitro-2-(trimethylsilylmethyl)thiophene with NaOMe–MeOH involves generation of the observable anion [5-O₂N·C₄H₂S· CH₂]^– with a solvent isotope effect k(MeOH)/k(MeOD) of 0.5, followed by protonation of the anion with a solvent isotope effect of 10; the results confirm that cleavages of RSiMe₃ compounds by NaOMe–MeOH involve separation of the anions R^–, and that the isotope effect in the reaction of R^– with MeOH depends greatly on the degree of conjugative delocalization of the negative, not just on the acidity of Rh.