Recent applications of intramolecular Diels–Alder reaction in total synthesis of natural products

Abstract

Diels–Alder (D–A) reaction is undoubtedly the most powerful [4 + 2] cycloaddition reaction in organic synthesis.

Total synthesis of natural products containing benzofuran rings

“…89 In recent years, we have highlighted the applications of several name reactions in the total synthesis of biologically active natural products and applications of asymmetric synthesis in total synthesis of natural products. [90][91][92][93][94][95] In this line very recently, we focused on chemistry of benzofurans and published a chapter in Advances in Heterocyclic Chemistry entitled the recent advances in the synthesis of benzo [b]furans. 78 Due to the massive number of pertinent references, coverage of the chemistry of this key heterocycle from different aspects, features and issues were surpassed by the limits in length and pages imposed by the editorial board of this book series.…”

First intramolecular Diels–Alder reactions using chromone derivatives: synthesis of chromeno[3,4-b]xanthones and 2-(benzo[c]chromenyl)chromones

“…7 Inspired by the versatility of an intermolecular DA reaction, intramolecular DA reactions has also been employed in the total synthesis of several polycyclic natural products, using one or multiple step strategies. 8 Although some chromone derivatives such as 2-or 3-styrylcromones have been involved in DA reactions, either as dienes or dienophiles, [9][10][11][12] to the best of our knowledge, there are no reports involving chromone derivatives in intramolecular DA reactions. Thus, following our previous reports dealing with the reactivity of (E)-2-(4-arylbut-1-en-3-yn-1-yl)chromones and (E,E)-2-(4-arylbuta-1,3-dien-1-yl)chromones in DA reactions, 13,14 herein we envisaged the synthesis of novel propargyloxychromone derivatives to be used as substrates in intramolecular DA reactions.…”

Et2NH/H2O catalyzed tandem aldol condensation - Diels-Alder cycloaddition sequence for the one-pot synthesis of (2R,3S)-rel-3-aryl-1,2,3,4,5,6,7,8-octahydro-6,6-dimethyl-8-oxo-2-naphthalenecarboxylates

“…In the presence of water and catalytic quantities of diethylamine, the intermediate diene was formed in situ. Addition of methyl acrylate (4) and dilute HCl to the mixture led to 75% formation of cis 5a after 11 h (entry 1). Use of different quantities of the amine showed that 25 mol% would be the optimum amounts (entries 2-4).…”

“…The 4+2 Diels-Alder (DA) reaction 1 is one of the most widely used organic transformations in synthetic organic chemistry [2][3][4] since it has the potential to construct a six-membered ring via simultaneous formation of two carbon-carbon bonds. In addition, the reaction can lead to the creation of up to four stereogenic centers with predictable stereoselectivity in a one step operation.…”