Hypervalent Iodine Oxidation of Allenes: Synthesis of 3-Acetoxy-3-alkoxypropynes, 2-Alkoxy-3-tosyloxypropanals and Phenyl-Substituted Propenals and Propenones

1-Alkoxyallenes yield 3-acetoxy-3-alkoxypropynes upon oxidation with [(diacetoxy)iodo]benzene at - 78-degrees-C in dichloromethane. Treatment with [hydroxy(tosyloxy)iodo]benzene under similar conditions gives 2-alkoxy-3-tosyloxypropanals. Phenyl-substituted propenals and propen-1-ones are obtained from the treatment of phenyl-substituted allenes with [hydroxy(tosyloxy)iodo]benzene in dichloromethane at - 78-degrees-C.