acid (TFA)-mediated cascadeoxidation/1,3-dipolarcycloaddition reaction of stabilized pyridinium salts with dimethyl sulfoxide (DMSO) has been developed in the presence of K2S2O8 and trimethylethylenediamine (TMEDA). In this transition-metal-free reaction, DMSO acts as a one-carbon source, thus providing a convenient method for the efficient and direct synthesis of various indolizine derivatives.
An I2/tert‐butyl hydroperoxide (TBHP)‐mediated [2+1+1+1] cycloadditions/oxidative aromatization reactions for the synthesis of indolizines using the one‐pot cascade process have been developed. A variety of aryl methyl ketones react with pyridine/isoquinoline and TBHP in the transition‐metal‐free reaction. This method utilizes readily available starting materials and TBHP acted in this reaction not only as oxidant and radical initiator but also as a methylene source, therefore providing a novel method of atom economy for the synthesis of indolizines.