Ring-opening Reaction of Oxiranes, Oxetanes, and Tetrahydropyran by Mercury(II) Salts and Alkyl Halides

The reaction of primary and secondary alkyl halides with mercury(II) acetate in oxiranes, oxetanes, and tetrahydropyran results in ring-opening to give the corresponding alkoxyalkyl acetates. Similar reactions with mercury(II) thiocyanate in oxetanes afford alkoxyalkyl isothiocyanate and thiocyanate, ROCH2C(R′)2CH2NCS and ROCH2C(R′)2CH2SCN, where the isomer ratios (N/S ratios) are 82–96/4–18. It is suggested that the reactions involve the initial formation of a three-, four-, or six-membered O-alkyloxonium ion intermediate and subsequent attack by XHgZ2−.