Facile access to [1,2]-oxazine derivatives <i>via</i> annulations of aminoxy-tethered 1,7-enynes

Chada, Raji Reddy; Kajare, Roshan Chandrakant; Bhandari, Mayur C.; Mohammed, Siddique Z.; Khatravath, Mahender; Warudikar, Kamalkishor; Punna, Nagender

doi:10.1039/d0ob02279a

Cited by 6 publications

(7 citation statements)

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“…In 2021, an efficient Ru‐catalyzed ring‐closing enyne metathesis reaction of linear N ‐ O tethered 1,7‐enynes has been disclosed by the Punna group (Scheme 53). [69] The annulation protocol, which occurred in the presence of Grubbs‐(II) (5 mol%) in toluene, afforded a direct approach to access structurally diverse 1,2‐oxazines in good to excellent yields. This strategy featured the advantages of good functional group compatibility, high atom economy, and gram‐scale capacity.…”

Section: Transition Metal‐catalyzed Reaction Of 17‐enynesmentioning

confidence: 99%

“…In 2021, the Punna and co‐authors reported a direct and novel protocol for the construction of vinylated‐[1,2]oxazines in the presence of Co 2 (CO) 8 in DCE at 80 °C for 12 h (Scheme 59). [75] The cobalt‐catalyzed protocol proceeded through a sequential oxyamination and Pauson‐Khand reaction sequences, leading to the functionalized cyclopenta[ d ][1,2] oxazines in good yields. It is worth noting that the raw material aminoxy‐tethered 1,7‐enynes were synthesized from propargyl alcohols.…”

Section: Transition Metal‐catalyzed Reaction Of 17‐enynesmentioning

confidence: 99%

“…Of note, the synthetic applicability of this reaction was highlighted by the introduction of stereochemical complexity and structural diversity through derivatizations of the In 2021, the Punna and co-authors reported a direct and novel protocol for the construction of vinylated- [1,2]oxazines in the presence of Co 2 (CO) 8 in DCE at 80 °C for 12 h (Scheme 59). [75] The cobalt-catalyzed protocol proceeded through a sequential oxyamination and Pauson-Khand reaction sequences, leading to the functionalized cyclopenta[d] [1,2]…”

Section: Co-catalyzed Reaction Of 17-enynesmentioning

confidence: 99%

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Recent Advances in the Cascade Cyclization Reactions of 1,7‐Enynes

Zhang,

Han,

Liang

2023

Adv Synth Catal

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Elaborated molecular architectures, especially carbocyclic, heterocyclic, endocyclic, and polycyclic molecular structures, serve as an important class of organic complexes because they are frequently occurring core structural units in a variety of biologically and pharmacologically relevant natural products, drug molecules, agrochemicals, and functional materials. A main challenge of current synthetic approaches is the development of strategically efficient and selective formation of these compounds from easy‐to‐handle starting materials. The cascade cyclizations of 1,7‐enynes have afforded an indispensable method for accessing molecular complexity and diversity, thus highlighting their potential significance in both academic and industrial communities. In the last decades, tremendous efforts have been devoted to discovering convenient routes to access sophisticated annulation derivatives, and a wide range of powerful and straightforward synthetic strategies have been reported. In this review, the latest achievements in the cascade cyclization reactions of 1,7‐enynes are summarized, which could be separated into three categories: (1) Visible‐light‐induced reactions of 1,7‐enynes; (2) Metal‐free catalyzed reactions of 1,7‐enynes; (3) Transition‐metal‐catalyzed reactions of 1,7‐enynes.

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Section: Transition Metal‐catalyzed Reaction Of 17‐enynesmentioning

confidence: 99%

Section: Transition Metal‐catalyzed Reaction Of 17‐enynesmentioning

confidence: 99%

Section: Co-catalyzed Reaction Of 17-enynesmentioning

confidence: 99%

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Recent Advances in the Cascade Cyclization Reactions of 1,7‐Enynes

Zhang,

Han,

Liang

2023

Adv Synth Catal

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“…1,2-Oxazines and their benzo-fused derivatives are embedded in many drugs and bioactive natural products. Their synthetic strategies, which are used as intermediates in synthesis due to their biological potential, have been comprehensively reported [ 1 , 2 , 3 , 4 , 5 , 6 ]. Analogues of 1,2-oxazine, peri- annelated to naphthalene, are not abundant in the literature.…”

Section: Introductionmentioning

confidence: 99%

“…Analogues of 1,2-oxazine, peri- annelated to naphthalene, are not abundant in the literature. The first naphtho[1,8- de ][ 1 , 2 ]oxazine to be synthesized was produced by the cyclodehydration of 6,6′,7,7′-tetramethoxygossypol dioxime [ 7 ]. Analogous reactions produced more derivatives [ 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

Naphtho[1,8-de][1,2]Oxazin-4-ol: Precursor to 1,2,8-Trisubstituted Naphthalenes and 1-Unsubstituted Naphtho[1,2-d]isoxazole 2-Oxide: A Novel Isomerization of the N-Oxide to Nitrile Oxide en Route to Isoxazol(in)es

Gerontitis,

Tsoungas,

Varvounis

2023

Molecules

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Naphtho[1,8-de][1,2]oxazin-4-ol and its acyl or benzyl derivatives ring open to various 2,8-dihydroxy-1-naphthonitriles, which, through (de)protection protocols and reduction, afford the target (E)-2-hydroxy-8-methoxy-1-naphthaldehyde. This was converted to its corresponding oxime, which was oxidatively o-cyclized with phenyliodine(III) diacetate (PIDA) to 9-methoxynaphtho[1,2-d]isoxazole 2-oxide. The latter, in deuterated DMSO at room temperature, was rearranged to its isomer 2-hydroxy-8-methoxy(naphthalen-1-yl)nitrile oxide. The isomerization was detected by time-course plot 1H NMR spectroscopy and further identified from its 13C NMR and HRMS spectra. The nitrile oxide was stable in (non)deuterated DMSO for at least 18 h. A 3,4-bis(2-hydroxy-8-methoxynaphthalen-1-yl)-1,2,5-oxadiazole 2-oxide, as a dimerization product or an isocyanate as a rearrangement isomer, was ruled out, the former by its HRMS spectrum and the latter by its 1,3-dipolar cycloaddition reactions to substituted isoxazoles.

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Mn‐Mediated Radical Cascade Cyclization of 1,6‐Enynes with Arylboronic Acids to Access Dihydrobenzo[b]fluorenones

2022

Self Cite

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Herein, we report the synthesis of functionalized dihydro-benzo[b]fluorenones through a manganese-mediated cascade radical cyclization of β-alkynyl propenones [1,6-enynes] with arylboronic acids. In the present strategy, the in-situ generated aryl radical undergoes chemo-selective addition followed by 5exo-trig cyclization. The reaction is emphasized by high atom-and step-economy with the construction of three new CÀ C bonds to access the dihydrobenzo[b]fluorenones in 68-81% yield under mild reaction conditions. The synthetic efficacy of the developed method is evidenced by the construction of new CÀ C and CÀ N bonds.

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Facile access to [1,2]-oxazine derivatives via annulations of aminoxy-tethered 1,7-enynes

Abstract: Highly diastereoselective construction of functionalized cyclopenta[d][1,2]oxazines is achieved from 1-aryl propargyl alcohols via sequential oxyamination/annulation reactions.

Cited by 6 publications

References 78 publications

Recent Advances in the Cascade Cyclization Reactions of 1,7‐Enynes

Recent Advances in the Cascade Cyclization Reactions of 1,7‐Enynes

Naphtho[1,8-de][1,2]Oxazin-4-ol: Precursor to 1,2,8-Trisubstituted Naphthalenes and 1-Unsubstituted Naphtho[1,2-d]isoxazole 2-Oxide: A Novel Isomerization of the N-Oxide to Nitrile Oxide en Route to Isoxazol(in)es

Mn‐Mediated Radical Cascade Cyclization of 1,6‐Enynes with Arylboronic Acids to Access Dihydrobenzo[b]fluorenones

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