ALTERNATION OF STEREOCONTROL MODE IN THE CYCLIZATION OF 2-(3',4'-DIMETHYL-6'-TRIMETHYLSILYL-4'-HEXENYL)-2-CYCLOHEXENONES BY THE AUXILIARY CONTROLLING SUBSTITUENTS AT 1'-POSITION AND 2'-POSITION OF THE SIDE-CHAIN

With the aim to alter the stereochemical mode in the cyclization of the title compound the diastereoselectivities in that of the substrates with an oxy-substituent at 1' and 2' positions of the side chain were investigated. In the cyclization of the substrate with the 2'-oxy-substituent its controlling effect was not enough to reverse the diastereoselectivity. On the other hand the cyclization of the substrates with the 1'-oxy-substituent proceeded under its ensuing elimination to afford the octalone derivatives with a variety of stereochemical outcomes. Through the choice with respects to kinds and stereochemistry of the oxy-substituent, and the Lewis acids, the respective stereoselective formations of the three diastereomers out of four including the octalone derivative with 8,9-trans-dimethyl configuration were achieved.