2-Aminooxazoles as novel dienophiles in the inverse demand Diels–Alder reaction with 1,2,4-triazines

Sustainable Solvent-Free Diels-Alder Approaches in the Development of Constructive Heterocycles and Functionalized Materials: A Review

The Diels-Alder reaction (DAR) is found in myriad applications in organic synthesis and medicinal chemistry for drug development, as it is the method of choice for the expedient synthesis of complex natural compounds and innovative materials including nanomaterials, graphene expanses, and polymeric nanofibers. Furthermore, the greatest focus of attention of DARs is on the consistent reaction procedure with stimulus yields by highly stereo- and regioselective mechanistic pathways. Therefore, the present review is intended to summarize conventional solvent-free (SF) DARs for the expedient synthesis of heterocyclic compounds and materials. In particular, this review deals with the DARs of mechanochemical grinding, catalysis (including stereoselective catalysts), thermal, and electromagnetic radiation (such as microwave [MW], infrared [IR], and ultraviolet [UV] irradiation) in SF procedures. Therefore, this comprehensive review validates the application of DARs to pharmaceutical innovations and biorenewable materials through consistent synthetic approaches.

Assessment on facile Diels-Alder approach of α-pyrone and terpenoquinone for the expedient synthesis of various natural scaffolds

The development of highly facile synthetic procedures for the expedient synthesis of complex natural molecules is always in demand. As this aspect, the Diels-Alder reaction (DAR) has a versatile approach to the synthesis of complex natural compounds and highly regio-/stereoselcetive heterocyclic scaffolds. Additionally, α-pyrone and terpenoquinone are two versatile key intermediates that are prevalent in various bioactive natural compounds for instance, (±)-crinine, (±)-joubertinamine, (±)-pancratistatin, (-)-cyclozonarone, and 8-ephipuupehedione, etc. Hence, the current review summarizes the Diels-Alder reaction application of α-pyrone and terpenoquinone to the constructive synthesis of various natural products over the past two decades (2001-2021). Equally, it serves as a stencil for the invention and development of new synthetic strategies for high-complex molecular structured natural and heterocyclic molecules.