A general method for the preparation of cumulenic ethers and thioethers

Abstract

Abstract Solutions of lithiated cumulenic ethers and bis‐ethers R 2 CHCCC(Li)OR 3 and R 1 OCHCCC(Li)OR 3 can be obtained by treatment of the compounds R 1 OCH(R) 2 )CCCH 2 OR 3 and R 1 OCH 2 CCCH(OR 3 ) 2 respectively with 2 equivalents of butyllithium in ether. Reaction of these solutions with H 2 O, D 2 O, methyl iodide, α‐chloro‐ethers or ketones gives the cumulenic compounds or their derivatives in good yields. Solutions of lithiated cumulenic thioethers R 2 CHCCC(Li)SR 3 are obtained in an analogous way, but hydrolysis affords the isomeric enynic thioethers R 2 CHCHCCSR 3 in addition to the expected cumulenic thioethers R 2 CHCCCHSR 3 . Elimination of R 1 OH from R 1 OC(R 2 ) 2 CCCH(SR 3 ) 2 with 1 equivalent of C 4 H 9 Li leads to the cumulenic dithioacetals (R 2 ) 2 CCCC(SR 3 ) 2 .