Recent Advances in the Synthesis of 2H-Pyrans

Tejedor, David; Delgado-Hernández, Samuel; Diana-Rivero, Raquel; Díaz-Díaz, Abián; García‐Tellado, Fernando

doi:10.3390/molecules24162904

Cited by 19 publications

(11 citation statements)

References 62 publications

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“…In our case, the use of aprotic polar solvent (DMSO) does not shift the equilibrium toward the ring-opened dienones as previously observed. 6 In summary, our studies have described the IBX oxidations of 3,5-hexadien-1-ols resulting in the formation of tetrasubstituted 2H-pyrans via the oxa-electrocyclization of 1-oxatriene intermediates.…”

Section: Scheme 1 Proposed Rationale For the Formation Of 2h-pyransmentioning

confidence: 79%

“…accessing 2H-pyrans as monocyclic as well as polycyclic structures via this cycloisomerization. 6 One reason for the instability of these substances is the observed valence isomerization between the 1-oxatrienes 1 and the ring-closed 2H-pyrans 2. Krasnaya 7 has described significant studies of steric and electronic factors that influence the equilibria of these interconversions.…”

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confidence: 99%

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IBX Oxidations for the Synthesis of Substituted 2H-Pyrans

Williams¹,

Bawel²,

Haddadpour³

et al. 2021

HETEROCYCLES

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Facile oxidation of highly substituted 3,5-hexadien-1-ols using 3-iodoxybenzoic acid (IBX) in DMSO has resulted in a one-pot preparation of 2,3,4,6-tetrasubstituted 2H-pyrans.Cycloisomerizations of the 1-oxatriene moiety, produced in the oxidation, spontaneously occur via a disrotatory oxa-electrocyclization. The 2H-pyran products of Table 1 features three differentiated carbonyl substituents. In Celebration of Professor Yasuyuki Kita on His 77th BirthdayThe pyran heterocycle is a common structural motif found within pharmaceuticals, agrichemicals, and biologically active natural products. Several reviews have summarized a variety of techniques for the preparation of substituted pyrans. 1 Methods for the synthesis of tetrahydropyrans have been extensivelyexplored, and we have previously described a general strategy using asymmetric S E ' allylation reactions for enantiocontrolled syntheses of substituted tetrahydropyrans 2,3 Similarly, the formation of dihydropyrans has attracted much attention because these structural motifs also appear within naturally-occurring macrolactones of biological interest. 4 While syntheses of tetrahydropyrans and dihydropyrans are often focused on issues of stereochemistry and efficient strategies for regiocontrolled substitutions, the increased unsaturation of 2H-pyrans results in the characterization of notably less stable species. Successful methods toward substituted derivatives of this reactive family of pyrans are generally limited in scope.In this communication, we report an efficient preparation of 2H-pyrans stemming from 3-iodoxybenzoic acid (IBX) oxidations of highly substituted 3,5-hexadien-1-ols with in situ electrocyclization. The formation of 2H-pyrans via the oxa-electrocyclization reaction has been reported by several investigators in the course of studies for natural product synthesis, 5 and a recent review has compiled key strategies for

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Section: Scheme 1 Proposed Rationale For the Formation Of 2h-pyransmentioning

confidence: 79%

mentioning

confidence: 99%

IBX Oxidations for the Synthesis of Substituted 2H-Pyrans

Williams¹,

Bawel²,

Haddadpour³

et al. 2021

HETEROCYCLES

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“…[ 9–11 ] These molecules form the structural motif of several synthetic as well as naturally occurring biologically active products including antibiotics, pheromones, alkaloids, and iridoids. [ 12–14 ] The pyran ring systems are extensively dispersed in the plants and animal kingdom. These are utilized as the fragrant preservatives in cosmetics and food stuffs.…”

Section: Introductionmentioning

confidence: 99%

Novel bisbenzopyronopyran derivatives: photochemical synthesis and their in‐vitro antimicrobial studies

Nisa

Yusuf

2020

Journal of Heterocyclic Chem

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The present research work describes the productive synthesis of novel bisbenzopyronopyran derivatives 4(a‐h) and 5(a‐h) via the photocyclization reactions of bischromones 3(a‐h) under the inert conditions. The latter compounds have been realized efficiently through the O‐alkylation reactions of the 3‐hydroxychromone 2 with suitable dihalogenated aliphatic/aromatic/heteroaromatic reagents in the presence of dry acetone/anhydrous K2CO3/Bu4N+I− (PTC). The cyclization reaction of chalcone 1 under the Algar‐Flynn‐Oyamada reaction conditions (KOH/H2O2) could results in the formation of compound 2 in the good yield. The structural scaffolds of the newly prepared bischromones and resultant bisbenzopyronopyrans have been certified from the meticulous analysis of their various spectroscopic parameters such as UV‐Vis, IR, 1H/13C‐NMR, and ESI‐MS. It was found that o/m/p‐xylene and pyridine‐linked final symmetrical bistetracycles exhibited higher antimicrobial potencies as compared to alkyl chain‐linked cyclized products. The bischromones 3(a‐h) could be able to endow modest level of antimicrobial behavior.

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“…The vastness of this topic is documented by four review articles.In their review, Stodulski and co-workers [2] highlight recent progress in the application of metal-free, visible-light-mediated catalysis for assembling five-and six-member heterocyclic scaffolds containing nitrogen and oxygen heteroatoms, particularly focused on the use of inexpensive organic dyes as an excellent alternative to the typical transition-metal complexes. García-Tellado's group [3] presents the nature of the different physicochemical factors affecting the valence isomerism between 2H-pyrans (2HPs) and 1-oxatrienes, and describes the most versatile synthetic methods reported in recent literature to access 2HPs. In more detail, a selection of the most transited routes able to generate these rings with a convenient amount of structural diversity, including the proper Knoevenagel reaction, the tandem propargyl Claisen rearrangement/H-shift reactions hosted by propargyl vinyl ethers [1,3], the cycloisomerization of diynes, and the Stille coupling of vinyl iodides and vinyl stannanes, is reported.…”

mentioning

confidence: 99%

“…García-Tellado's group [3] presents the nature of the different physicochemical factors affecting the valence isomerism between 2H-pyrans (2HPs) and 1-oxatrienes, and describes the most versatile synthetic methods reported in recent literature to access 2HPs. In more detail, a selection of the most transited routes able to generate these rings with a convenient amount of structural diversity, including the proper Knoevenagel reaction, the tandem propargyl Claisen rearrangement/H-shift reactions hosted by propargyl vinyl ethers [1,3], the cycloisomerization of diynes, and the Stille coupling of vinyl iodides and vinyl stannanes, is reported. The contribution of Lee and his group [4] provides an overview of the biological roles and synthetic strategies of saturated cyclic ethers, covering some of the most studied, and newly discovered, related natural products in recent years.…”

mentioning

confidence: 99%