1: tert-butyl thiopropionate With N,N,N',N',N'',N''-hexamethylphosphoric triamide; lithium diisopropyl amide T=-78°C; 0.25 h; 2: chloro-trimethyl-silane T=-78 - 20°C; Further stages.;

lithium diisopropyl amide in tetrahydrofuran T=-78°C;