Electrophilic cyclization of cyclopropylideneallenyl ketones in the presence of I_2/CuI offers an efficient and straightforward route to highly substituted furans under mild reaction conditions. Further transformation of the resulting iodofurans provides structurally more advanced furan derivatives.

A transition-metal-free tandem O-arylation/hydroxylation approach has been developed for the efficient synthesis of highly substituted 2-hydroxyflavanones from triazenylaryl-substituted diketones. The intermediate benzopyrylium cation may be involved in these reactions.

A simple and highly efficient reaction promoted by Lewis acid has been demonstrated for the synthesis of dibenzopyranones. The metal-free annulation can tolerate a series of functional groups and also allows the synthesis of coumarins and phenanthridinones in good to excellent yields.

A Lewis-acid-promoted approach to the synthesis of highly functionalized dihydrobenzofuran derivatives was developed. A diverse range of functional groups are tolerated in this type of reaction. The reaction mechanism investigation indicates that the highly reactive phenyl cation intermediate is probably involved in this process. The chirality of substrate is retained under the reaction conditions.