An efficient synthesis of hindered alkyl and aryl neopentyl ethers

As a rule, the S(N)2 reactions of neopentyl bromide and tosylate with sodium alkoxides are extremely retarded by steric hindrance, and the yields of alkyl neopentyl ethers are poor because of side reactions such as neopentyl rearrangement, elimination, and decomposition. However, this report deals with a highly selective synthesis of alkyl and aryl neopentyl ethers. We found that the above side reactions were successfully overcome by the use of neopentyl iodide and potassium alkoxide in the mixed solvent of DMSO or DMI-alcohol (1/1 similar to 1/2) at 110-140 degrees C. Especially, potassium benzyl oxide and triphenylmethoxide, which are stabilized by delocalization of electron, afforded the corresponding alkyl neopentyl ethers almost quantitatively under optimum conditions. On the other hand, the reactions of alkali metal aryl oxides with neopentyl iodide, tosylate, and mesylate were carried out in DMSO, DMF, and DMI. The desired aryl neopentyl ethers were readily given in substantially quantitative yields.