Abstractl‐Alkoxy‐l‐(α‐hydroxyalkyl)allenes R1CH=C=C(OR2)C(OH)R3R4(Ia) have been converted with high yields into 3‐alkoxy‐2,5‐dihydrofurans (II) using potassiumtert‐butoxide in dimethyl sulfoxide. Hydrolysis of II with dilute sulfuric acid afforded 3‐oxotetrahydrofuran derivatives III. l‐(β‐Hydroxyalkyl)‐l‐methylthioallenes R1CH=C=C(SCH3)CH2CH2OH (IVb) and the analogous oxygen compounds IVa yielded 2‐alkyl‐3‐methylthio‐4,5‐dihydrofurans (Vb) and a mixture of 3‐methoxy‐2‐methyl‐4,5‐dihydrofurans (Va) and 3‐methoxy‐2‐methylenetetrahydrofuran VI, respectivel