Synthesis of enantiomerically pure (E)-1,1,3,3,6,6-hexamethyl-1-sila-4-cycloheptene and its absolute configuration

The title compound 1, a highly strained (E)-cycloalkene, was prepared in en antiomerically pure form from the corresponding trans-1,2-diol 4 via the th ionocarbonate 5. The racemic 4 was separated by enantioselective HPLC on an amylose tris(3,5-dimethylphenylcarbamate) column. The absolute configurati on of 1 was determined by circular dichroism spectroscopy in connection wit h theoretical calculations; the (+)-enantiomer has the (S)- and the (-)-ena ntiomer the (R)-configuration. (C) 1999 Elsevier Science Ltd. All rights re served.