Novel synthesis of pyridazino[4,5-b][1,4]oxazin-3,8-diones☆

Cho, Su Dong; Song, Sang Yong; Park, Yong Dae; Kim, Jeum Jong; Joo, Woo Hong; Shiro, Motoo; Falck, John R.; Shin, Dong Soo; Yoon, Yong Jin

doi:10.1016/j.tetlet.2003.09.216

Cited by 20 publications

(3 citation statements)

References 9 publications

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“…This was only achieved by chromatography after an extractive workup. The regiochemistry of products 7b – 7e was determined (see Scheme ) from the known mode of reactivity for the pyrazolyl phenols (phenolate first) and the 4,5‐dichloro‐3(2 H )‐pyridazinones (Cl at the 5‐position first) as well as the fact that the Smiles rearrangement had been observed in all similar condensations that we have studied3–5 and is well‐documented for 4,5‐dichloro‐3(2 H )‐pyridazinone substrates 16–18. (The universal character of the Smiles rearrangement that takes place in these condensations was further confirmed by X‐ray analysis of a new condensation product as described below.…”

Section: Resultsmentioning

confidence: 91%

Efficient Use of 1,2‐Dihaloazine Synthons in Transition‐Metal‐Free Preparation of Diverse Heterocycle‐Fused 1,4‐Oxazepines

et al. 2015

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A previously reported condensation reaction of ambiphilic 2‐(1H‐pyrazol‐5‐yl)phenols with various o‐chloro‐substituted nitroaromatic synthons to provide medicinally important tetracyclic pyrazolo[1,5‐d][1,4]oxazepines was extended to more readily available and convenient‐to‐use 1,2‐dihaloazines. Although 4,5‐dichloropyridazin‐3(2H)‐ones and 2,3‐dichloropyrazine are popular bis(electrophilic) partners in various SNAr‐type condensations and also were efficiently used in the reaction reported herein, the facility with which various 3‐bromo‐2‐chloropyridines underwent the same cyclization was unexpected. These reactions are presumed to occur as sequential intermolecular SNAr/Smiles rearrangement/intramolecular SNAr tandem reactions and provide a rare example of the transition‐metal‐free substitution of a bromine atom at the 3‐position of a pyridine ring.

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Section: Resultsmentioning

confidence: 91%

Efficient Use of 1,2‐Dihaloazine Synthons in Transition‐Metal‐Free Preparation of Diverse Heterocycle‐Fused 1,4‐Oxazepines

et al. 2015

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“…The Smiles rearrangement is a powerful and important tool for the construction of fused heterocycles. [13][14][15][16][17] In comparison with stepwise transformations, one-pot syntheses are much preferred due to their convenience. Consequently, the Smiles rearrangement has been introduced into onepot syntheses of fused heterocycle systems.…”

Section: Letter Syn Lettmentioning

confidence: 99%

One-Pot Highly Regioselective Synthesis of Indole-Fused Pyridazino[4,5-b][1,4]benzoxazepin-4(3H)-ones by a Smiles Rearrangement

Jiang

2018

Synlett

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A simple and convenient synthesis of indole-fused pyridazino[4,5-b][1,4]benzoxazepin-4(3H)-ones is described. A range of 2-(1H-indol-2-yl)phenols and 4,5-dichloropyridazin-3-ones are compatible with this reaction. A Smiles rearrangement is proposed as a key step in the highly regioselective construction of the products. The easy availability of the starting materials makes this an appealing method in organic synthesis.

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“…8 The same group also described the synthesis of pyridazino [4,5-b][1,4]oxazin-3,8diones via a similar process. 9 Afterwards, a wide range of diversified heterocycles were prepared based on this strategy. 10 The dibenzo [b,f ][1,4]oxazepine scaffolds are core structures in numerous biologically active compounds.…”

mentioning

confidence: 99%

Transition-metal-free synthesis of indole-fused dibenzo[b,f][1,4]oxazepines via Smiles rearrangement

Liu

Jia

et al. 2016

Org. Biomol. Chem.

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A one-pot transition-metal-free approach for the synthesis of indole-fused dibenzo[b,f][1,4]oxazepines from 2-(1H-indol-2-yl)phenol and 1,2-dihalobenzenes or 2 halonitroarenes has been developed. The proposed mechanism for this transformation features a Smiles rearrangement favoured over a direct intramolecular nucleophilic cyclization, which affords the corresponding products in different regioselectivities. This reaction also features simple reaction conditions and wide functional group tolerance.

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Novel synthesis of pyridazino[4,5-b][1,4]oxazin-3,8-diones☆

Cited by 20 publications

References 9 publications

Efficient Use of 1,2‐Dihaloazine Synthons in Transition‐Metal‐Free Preparation of Diverse Heterocycle‐Fused 1,4‐Oxazepines

Efficient Use of 1,2‐Dihaloazine Synthons in Transition‐Metal‐Free Preparation of Diverse Heterocycle‐Fused 1,4‐Oxazepines

One-Pot Highly Regioselective Synthesis of Indole-Fused Pyridazino[4,5-b][1,4]benzoxazepin-4(3H)-ones by a Smiles Rearrangement

Transition-metal-free synthesis of indole-fused dibenzo[b,f][1,4]oxazepines via Smiles rearrangement

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