O) originated from m/e 232 by loss of SO and SO,, respectively. Therefore, the composition of m/e 232 must be C,,H,,SO,. Loss of water was observed from mle 127 (metastable peak) and m/e 176 (Jennings). The silylation product [(trimethylsilyl)imidazole) of 8 showed mle 289, 290 and 291 with relative isotope intensities in agreement with C,,H,,SO,Si, as expected for (M -15) of the silyl ether of the alcohol C13H,,S03.
143(M' at m/e 304 absent.) The loss of one carbon atom (8) relative to the starting material lc was confirmed by I3C NMR. 13C NMR(CDC1,): 6 25.2, 30.1, 33.4 and 38.5 ppm (2 x tert-butyl), 6 124.6, 127.8 and 163.1 ppm The observed frequencies deviate sufficiently from that of thiete dioxide (72.3, 137.8 and 148.0 ppm) to preclude a four-membered ring structure.
R .A. Boissonnas, Helv. Chim Acta 34, 874 (1951) '