MECHANISMS OF HYDROLYSIS OF (TRIMETHYLSILYL) METHANESULFONYL CHLORIDE- SULFENE ENAMINE REACTIONS IN WATER

Kinetic, product analysis, and deuteration experiments are consistent with the following mechanisms of hydrolysis of (trimethylsilyl)methane sulfonyl chloride (1) (in 0.01 M KCl at 1-degrees-C): (a) pH less-than -or-equal-to 10.0, attack of water at silicon to form sulfene (5) whic h is trapped by water to give methanesulfonate anion (3), (b) pH great er-than-or-equal-to 10.0, attack of hydroxide anion (i) at silicon to yield sulfene (5) and (ii) at an alpha-hydrogen to form (trimethylsily l)sulfene (4), in each case followed by trapping of the sulfene to giv e either methanesulfonate (3) or (trimethylsilyl)methanesulfonate (6) salts. Aqueous potassium fluoride catalyzes the hydrolysis of 1 with f ormation of the methanesulfonate 3, evidently by way of silicophilic a ttack of fluoride anion on 1 with formation of sulfene (5). Reaction o f 1 with an enamine 7 in water (at pH 8 or 9), with or without fluorid e, gives two characteristic sulfene-enamine products, (i) the four-mem bered cycloadduct 8 and (ii) the methylsulfonyl aldehyde 9. The same o r related products are also obtained from methanesulfonyl, 2-propanesu lfonyl, and phenylmethanesulfonyl chlorides and enamines in water (at pH 9). Hydrolysis of 1 is also catalyzed by aniline or triethylamine e vidently giving 5.