Chemistry of acetylenic ethers 85: Preparation of compouds with a 3,5‐dien‐1‐yne system by 1,2 and 1,6 elimination of alcohols from various types of unsaturated ethers

Abstract

Abstract1,2 Elimination of HOR [R = CH3 or CH(CH3)(OC2H5)] from ethers of the types HCCCHCHCH2CH2OR and HCCCHC(CH3)CH2CH2OR, using an excess of potassium amide in liquid ammonia, affords the dienynes HCCCHCHCHCH2 and HCCCHC(CH3)CHCH2, respectively, in good yields.1,6 Eliminations of HOR [R = CH3, C2H5, n‐C4H9, n‐C6H13, CH(CH3)(OC2H5)] from the ethers H3CCCCHCHCH2OR and H3CCC‐C(CH3)CHCH2OR have also been effected with potassium amide. The yields of the dienynes HCCCHCHCHCH2 and HCCCHC(CH3)CHCH2 obtained in this manner were good, except in the cases where R = CH3 and C2H5. 1,6 Elimination of ethanol from H5C2SCH2CCCHCHCH2OC2H5 could be achieved under milder conditions, viz. with sodium ethoxide in liquid ammonia. The dienynyl thioether H5C2SCCCHCHCHCH2 was obtained in good yield. The same compound was prepared from hexadienyne HCCCHCHCHCH2, lithium amide and diethyl disulfide C2H5SSC2H5.