Stereoselective Transformation of 1-Alkenyl Ether (R~1CH = CHOMe) into Alkene (R~1CH = CHR~2) Based on Stereospecific Elimination of the Vicinal Iodo(methoxy)alkane

摘要

Treatment of alkenyl methyl ether with ICl rapidly gave 1-chloro-2-iodo-1-methoxyalkane quantitatively. Without isolation, this dihalide was treated with Et_3Al to afford anti-iodo(methoxy)alkane in good yield with high stereoselectivity. The stereochemistry of the starting alkenyl ether did not affect the stereochemical outcome of the product. The use of alkynylaluminum ((RC (ident to) C)_2AlEt) resulted in alkynylation of the #alpha#-chloro-#beta#-iodoether. Anti-iodo(methoxy)alkane was converted into (Z)-alkene upon treatment with n-BuLi in hexane-ether at -78 deg C. On the other hand, the reaction of the same anti-iodo(methoxy)alkane with allylsilane-TiCl_4 provided (E)-alkene.