“…This process was first reported in the 1960s, when Povarov et al. described the formation of two new C–C bonds from N -arylimines 3 with vinyl enolethers 4 under medium-strength Lewis acid catalysis (BF 3 ·OEt 2 ), thus obtaining substituted THQs 5 that were oxidized to the corresponding QUIN 6 (Scheme 1 ) [ 13 ]. Scheme 1 First example described by Povarov …”
Nitrogen heterocycles are part of the structure of natural products and agents with important biological activity, such as antiviral, antibiotic, and antitumor drugs. For this reason, heterocyclic compounds are one of today’s most desirable synthetic targets and the Povarov reaction is a powerful synthetic tool for the construction of highly functionalized heterocyclic systems. This process involves an aromatic amine, a carbonyl compound, and an olefin or acetylene to give rise to the formation of a nitrogen-containing heterocycle. This review illustrates advances in the synthetic aspects of the intramolecular Povarov reaction for the construction of intricate nitrogen-containing polyheterocyclic compounds. This original review presents research done in this field, with references to important works by internationally relevant research groups on this current topic, covering the literature from 1992 to 2022. The intramolecular Povarov reactions are described here according to the key processes involved, using different combinations of aromatic or heteroaromatic amines, and aliphatic, aromatic, or heteroaromatic aldehydes. Some catalytic reactions promoted by transition metals are detailed, as well as the oxidative Povarov reaction and some asymmetric intramolecular Povarov processes.
“…This process was first reported in the 1960s, when Povarov et al. described the formation of two new C–C bonds from N -arylimines 3 with vinyl enolethers 4 under medium-strength Lewis acid catalysis (BF 3 ·OEt 2 ), thus obtaining substituted THQs 5 that were oxidized to the corresponding QUIN 6 (Scheme 1 ) [ 13 ]. Scheme 1 First example described by Povarov …”
Nitrogen heterocycles are part of the structure of natural products and agents with important biological activity, such as antiviral, antibiotic, and antitumor drugs. For this reason, heterocyclic compounds are one of today’s most desirable synthetic targets and the Povarov reaction is a powerful synthetic tool for the construction of highly functionalized heterocyclic systems. This process involves an aromatic amine, a carbonyl compound, and an olefin or acetylene to give rise to the formation of a nitrogen-containing heterocycle. This review illustrates advances in the synthetic aspects of the intramolecular Povarov reaction for the construction of intricate nitrogen-containing polyheterocyclic compounds. This original review presents research done in this field, with references to important works by internationally relevant research groups on this current topic, covering the literature from 1992 to 2022. The intramolecular Povarov reactions are described here according to the key processes involved, using different combinations of aromatic or heteroaromatic amines, and aliphatic, aromatic, or heteroaromatic aldehydes. Some catalytic reactions promoted by transition metals are detailed, as well as the oxidative Povarov reaction and some asymmetric intramolecular Povarov processes.
“…It can be defined as an inverse electron-demand hetero Diels-Alder cycloaddition between N-arylimines and electron-rich olefins (Scheme 1), and is named after the Russian chemist L. S. Povarov who described it in the 1960s. 8 Despite its high potential importance, the reaction remained dormant for almost 30 years until Kobayashi reported the discovery of lanthanide triflates as its catalysts. 9 Thanks to the growing interest of synthetic chemists in this transformation, the scope of dienes and dienophiles applicable to the synthesis of tetrahydroquinolines by this method is now very broad and includes N-arylimines derived from either electron-rich or poor anilines and many types of carbonyl components, including α-ketoimines; cyclic or acyclic ethers and thioethers, enamines, enamides, alkenes and alkynes, among others, can play the role of dienophiles.…”
Catalytic asymmetric Povarov protocols have undergone an explosive growth, especially in the last ten years, since the first example was published in 1996. The use of chiral Lewis and Brønsted...
“…The first aza‐DAR was reported by Povarov with co‐authors in the mid‐1960s [13–15] . The authors founded that Schiff bases 1 underwent cycloaddition with linear or cyclic vinyl ethers 2 in the presence of a Lewis acid catalyst (BF 3 ⋅ OEt 2 ) to afford tetrahydroquinoline derivatives 3 in moderate to high yields (Scheme 2).…”
In this review, the pivotal achievements and recent advances in catalytic asymmetric aza‐DAR reported up to 2020 are retrospectively considered and their potency for enantioselective synthesis of useful chiral piperidine, quinoline, pyridazine, oxazine and oxadiazine derivatives and fused compounds of higher molecular complexity bearing these pharmacology‐relevant heterocyclic scaffolds is demonstrated. The reported data are systematized according both to key electron transfer modes (normal or invers electron demand reactions) and to main types of attainable heterocyclic products. Of significant attention are an analysis of activation strategies (complexation, enamine or enolate formation, H‐bonding, etc.) applicable to reactions with particular types of dienes and dienophiles and identification of plausible reaction pathways (either concerted or stepwise) over stereoselective cyclization processes. The review contains 310 references and 122 synthetic schemes.
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