A Selective Synthesis of Hindered 1-Adamantyl t-Alkyl Ethers

The SN reactions of t-alkyl alcohols with 1-adamantyl methanesulfonate and amines (molar ratio 10/1/1) were carried out at 80 - 100 °C under a nitrogen atmosphere. The corresponding products were obtained in 59- 94% yields, i.e., 1-adamantyl t-butyl ether (90%), 1-adamantyl t-pentyl ether (86%), 1-admametl 1, 1-diethylpropyl ether (82%), 1-adamantyl 1, 1-dipropylbutyl ether (59%), 1-adamantyl, 1-adamantyl 1-methyl-1-phenylethyl ether (71%), 1-adamantyl 1, 1-dimethy1-2-propenyl ether (90%), and 1-adamantyl 1, 1-dimethyl-2-propynyl ether (94%). In spite of the steric hindrance of t-alkyl alcohol and 1-adamantyl substrate, the yields o f the ethers were good to excellent. However, 1-adamantyl iodide was much less reactive than 1-adamantyl methanesulfonate even under severe conditions. The electronic effect of the functional group of t-alkyl alcohol was also exhibited. The optimum reaction conditions were examined, and the reaction mechanism was proposed.