Dearomatization of furans in the synthesis of heterocycles

Abstract

Due to low energy of aromaticity, furan substrates may undergo chemical transformations that are unusual to those of arenes or other heterocycles. In such transformations furan nucleus may serve as masked 1,3 diene, enol ether or 1,4-dicarbonyl compound. This unique reactivity allows furans to be utilized in synthesis of a large variety of useful products, from alkanes to prostaglandines. Nitrogencontaining heterocycles are considered as ones of the most important among organic molecules, thus this is highly attractive to develop new synthetic routes toward such heterocyclic systems based on the utilization of so-called “furan platform”. That would provide an inexpensive way toward valuable objects exploiting products of biomass processing. During the last decade we have developed general synthetic approaches toward functionalized heterocycles based on the furan rearrangement strategy [1–7]. Recent results, discussion on mechanisms of specific transformations along with the scope and limitations of furan rearrangements into diverse polysubstituted heterocycles will be given.