The intramolecular Diels-Alder strategy: Applications to total synthesis of natural products

The Diels-Alder reaction is one of the most valuable reactions in synthetic organic chemistry. This [4 + 2] cycloaddition produces a cyclohexene derivative with concomitant generation of up to four new stereogenic centers. Particularly, intramolecular version has attracted many organic chemists due to forming polycyclic skeleton with high regio- and stereoselectivity under mild conditions. Thus, the intramolecular Diels-Alder reaction has shown its broad utility for the construction of various complex ring systems. In this review, we summarize the regio-, endo/exo, and/or π-facial selective intramolecular Diels-Alder reactions of type I for total synthesis of natural products, which have been published in recent years.