POLYSULFONYLAMINES .36. TRIMETHYLSILYL DIMESYLAMINE - PREPARATION, NMR-SPECTROSCOPIC CHARACTERIZATION, AND REACTIVITY AS A SILYLATING AGENT

(CH3)3SiN(SO2CH3)2 (1), m.p. 69-70-degrees-C, is obtained by metathesis of AgN(SO2CH3)2 with (CH3)3SiCl (improvement of a known procedure) or, more conveniently, by silylation of HN(SO2CH3)2 with [(CH3)3Si]2NH. The H-1, C-13, and Si-29 NMR solution spectra and the Si-29 NMR solid-state spectrum suggest the constitution of 1 in solution (CDCl3, CD2Cl2, CDCl2-CDCl2) to be an equilibrium mixture of the N-silylated form (CH3)3Si-N(SO2CH3)2 (I) and the O-silylated form (CH3)3Si-O-S(O)(CH3)=NSO2CH3 (II) in a molar ratio of 2:1 at room temperature, whereas in the known crystal structure of 1 only form I is present. The solid-state NMR experiment acted as a bridge between X-ray crystallography and solution-state NMR, enabling assignments of the resonances to be made with confidence to the tautomers. At room temperature, form II undergoes a rapid intramolecular 1.5-migration of silicon between oxygen centers of the two sulfonyl groups. As shown by kinetic measurements using H-1 NMR spectroscopy, 1 is a highly reactive agent for silylating ketones in the presence of triethylamine. Hydroxy and thiol functions, even when sterically hindered, are silylated by 1 in uncatalyzed reactions. It is further shown that HN(SO2CH3)2 is an efficient catalyst for silylations with [(CH3)3Si]2NH.