Tetrahedron Letters,Vol.26,No.l9,pp 2259~.2262,1985 0040-4039/85 $3.00 + .OO Printed in Great Britain 81985 Pergamon Press Ltd. zyxwvutsrq SERENDIPITOUS SYNTHESIS OF ALKYL TRIMETHYLSILYLDITHIOFORMATES BY TRAPPING OF BIS(TRIMETWLSILYL)THIONE WITH ALEANESULFENIC ACIDS. SYNTHESIS OF BIS- AND TRIS(TRIMETHYLSILYLbfETHANETHIOLS.l Eric Block* and Mohammad Aslam Department of Chemistry, State University of New York at Albany, Albany, New York 12222 Abstract: Tris(trimethylsilyl)methanethiol, prepared from tris(trimethylsilyl)methane, can be easily converted into bis(trimethylsilyl)methanethiol and this to bis(trimethylsilyl)methyl alkanethiosulfinate esters; the latter upon heating afford alkyl trimethylsilyldithioformates via bis(trimethylsilyl)thione, which can be trapped with dienes. As part of a study of the synthesis and chemistry of substances bearing both silicon and sulfur functionalities on the same carbon atom ’ we have been examining synthetic routes to d- silyl thiocarbonyl compounds. 2b Bis(trimethylsilyl)thione, L, the silicon counterpart of the stable, well studied di-tert-butylthione, particularly interested us. Among several possible approaches to this thione, thermolysis of bis(trimethylsilyl)methyl alkanethiosulfinates, 2 (eq l), seemed particularly attractive. 3 We report herein the preparation of 2 via the inter- H -1) (Me3Si )2&SR heat S -> (Me3Si)2C=S + RSOH (1) 1; 1 = esting new compounds bis- and tris(trimethylsilyl)methanethiols, 4 and 1, respectively, and our novel finding that upon heating, 4 gives in good yield previously unknown alkyl trimethyl- silyldithioformates (dithiocarbalkoxytrimethylsilanes) Me3SiC(S)SR, 2, by way of thione I. Preparation of thiosulEinate 2 required thiol 3. This thiol may be easily prepared from the previously unknown, hindered thiol, 2. Thus, treatment of tris(trimethylsilyl)methane 4P with methyllithium and then elemental sulfur gives 3 in 46% yield after extractive purifica- tion with methanol-KOH followed by sublimation. Heating thiol 2 in a sealed tube at 230-240” C for several hours followed by acid hydrolysis gives pure thiol & in 85% yield (eq 2).5 MeLi; SS; H+ 230” c + (Me3Sij3CH > (Xe3Si)3CSH -3 (Me3Si)2CHSSiMe3 H (Me3Si)2CHSH (2) P 5 = L 4 2259