Recent advances in the syntheses of pyrroles

The pyrrole moiety is an important structural motif in functional materials, natural products, and pharmaceuticals. More and more synthetic strategies toward pyrroles have emerged, where various efficient building blocks are developed and these synthons enable the syntheses of pyrroles with different numbers of components. However, no review specifically summarizes the syntheses of pyrroles according to the type and number of employed building blocks. To aid researchers to design appropriate substrates for pyrrole synthesis, herein we summarized the advances in pyrrole syntheses and classified these reactions into four categories according to the number of employed components, which may shed light on developing more efficient synthetic methods toward substituted pyrroles.