SYNTHESIS OF THE 1ST STABLE 1,2-SILATHIETANE

Sulfur reacts with 1,1-di-tert-butyl-2,3-di-methylsilirane (1) to produce the first isolable silthietane, 1,1-di-tert-butyl-3,4-dimethyl-1,2-silathietane (2), and 1,1-di-tert-butyl-3,4-dimethyl-1-sila-2;3-dithiacyclopentane (3) in 60% and 19% yields, respectively. Pyrolysis (200 °C) of 2 generates 1,1,3,3-tetra-tert-butyl-2,4-dithiadisilacy-clobutane (4) and 1,1,3,3-tetra-tert-butyl-5,6-dimethyl-2,4-dithia-1,3-disilacyclohexane (5). 4 is formally the dimer of the reactive intermediate di-tert-butylsilathione, t-Bu2Si═S, and 5 is the product of insertion of the silathione fragment into 2. When 1 is heated in the presence of hexamethylcyclotrisiloxane, 1,1-di-tert-butyl-3,3,5,5,7,7-hexamethyl-2,4,6-trioxa-1,3,5,7-tetrasila-8-thiacyclooctane (6) is formed. Sulfur insertion into 1 to produce 2 is stepwise, as is the cleavage of 2. © 1990, American Chemical Society. All rights reserved.