A general method for the preparation of cumulenic ethers and thioethers

Abstract
Solutions of lithiated cumulenic ethers and bis‐ethers R2CHCCC(Li)OR3 and R1OCHCCC(Li)OR3 can be obtained by treatment of the compounds R1OCH(R)2)CCCH2OR3 and R1OCH2CCCH(OR3)2 respectively with 2 equivalents of butyllithium in ether. Reaction of these solutions with H2O, D2O, methyl iodide, α‐chloro‐ethers or ketones gives the cumulenic compounds or their derivatives in good yields.Solutions of lithiated cumulenic thioethers R2CHCCC(Li)SR3 are obtained in an analogous way, but hydrolysis affords the isomeric enynic thioethers R2CHCHCCSR3 in addition to the expected cumulenic thioethers R2CHCCCHSR3. Elimination of R1OH from R1OC(R2)2CCCH(SR3)2 with 1 equivalent of C4H9Li leads to the cumulenic dithioacetals (R2)2CCCC(SR3)2.

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