Article

Abstract

Lithium (E)-1-hexenesulfenate (5a) was treated with a number of TMS-X (TMS = trimethylsilyl) reagents to afford N,N-bis(trimethylsilyl)-(E)-1-hexenesulfenamide (7a) and (or) di((E)-1 hexenyl) disulfide (8), usually in low yield. The cleanest reactions, those from use of TMS-Cl (to afford 7a) and TMS-CN (which yields 8) were analyzed by variable temperature NMR. It was found that the low-temperature silylation reaction using TMS-Cl affords 7a and thiosulfinate 12 as initial products. Warming the mixture coerces the decomposition of 12. Treatment of 5a with TMS-CN also yields thiosulfinate 12 which is reduced to disulfide 8 as the temperature warms, possibly by action of cyanide ion. Evidence is presented that allows a confident structural assignment of the transient thiosulfinate 12, and mechanisms are suggested for the formation of 12. The study also led to the NMR observation of (E)-1-hexenesulfenate (5a).Key words: sulfenate, thiosulfinate, variable temperature NMR (VT NMR), silylation.