Abstract: In the last few years we have extensively studied the base-promoted isomerization of oxiranyl ethers showing that they can be stereoselectively converted in a number of synthetically useful products by treatment with mixed metal reagents (superbases) [1,2]. Depending on the substrate and the base used oxiranyl ethers 1 can be transformed into hydroxy enethers 2 [3,4] (R’= H), di- and trisubstituted oxetanes 3 via a 4-endo process [5-7] (R’= H or alkyl), 1,4-diols 4 using an excess of base [8], tetrahydrooxepines 5 (R’’= CH=CH2) [9] and terminal allylic alcohols 7 (R’’= SPh) when radical anions are used. The use of superbasic mixtures is essential in order to have processes with a highly regio- and stereoselective behaviour and high yields of converted products.