Oxepanes and Oxepines

Belenkii, L. I.

doi:10.1016/b978-008044992-0.01202-5

Cited by 11 publications

(11 citation statements)

References 480 publications

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“…Consequently, two main groups of reactions can be considered in general terms: addition and cycloaddition reactions and the cleavage of the oxepine ring. This reactivity has been covered extensively in Comprehensive Heterocyclic Chemistry, I, II and III [2,4,7] and the present section is intended to provide only a summary and update. The oxepine-benzene oxide (5a/5b) system is also attractive for photochemical studies, because the equilibrium varies with the solvent polarity and, to some extent, with the temperature.…”

Section: Reactivity Of Oxepinesmentioning

confidence: 99%

“…To understand the role of the heteroatom on the rate of hydroboration, Brown and co-workers [326] 4 -+ 2,3,4,5-tetrahydrooxepine reacts 30 times slower than cycloheptene (Table 21.5), and the hydroboration with 9-borabicyclo[3.3.1]nonane (9-BBN) is exclusively directed to the 3-position, which is probably controlled by a strong mesomeric contribution of the oxygen (Table 21.5, Scheme 21.157).…”

Section: Tetrahydrooxepinesmentioning

confidence: 99%

“…N-Substituted 1H-azepines are oils or stable solids with well-defined melting points. Azepane (7) was first obtained in 1963 and is a typical secondary amine with a pK a of 11.29 [59].…”

Section: Relevant Natural and Useful Compoundsmentioning

confidence: 99%

“…Partially saturated seven-membered heterocycles can be viewed as derivatives or related systems of these two main seven-membered heterocyclic units arising from carbon replacement in cycloheptatriene and in cycloheptane. Replacement of the sp 3 hybridized carbon atom in cycloheptatriene by a nitrogen leads to an azacycloheptatriene known as 1H-azepine (1) and the corresponding 2H-, 3H-, and 4H-azepines (2)(3)(4) are the tautomeric forms generated by the replacement of the sp 2 carbons. 1H-Azepine is an unstable red oil that is prone to rearrange to the also unstable 3H-azepine in the presence of acids and bases.…”

Section: Introductionmentioning

confidence: 99%

“…Two other interesting systems are the sulfur-oxidized forms of 6 and 9, which are known as thiepine 1,1-dioxide (10) and thiepane 1,1-dioxide (11), respectively. The chemistry and properties of most common seven-membered heterocycles have been reviewed in previous surveys, mainly in Comprehensive Heterocyclic Chemistry I [1,2], Comprehensive Heterocyclic Chemistry II [3][4][5] and Comprehensive Heterocyclic Chemistry III [6][7][8]. Other reviews on azepines have been published [9][10][11] and benzazepines have been covered in a reference series [12].…”

Section: Introductionmentioning

confidence: 99%

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Seven‐Membered Heterocycles: Azepines, Benzo Derivatives and Related Systems

Vaquero

Cuadro

Herradón

2011

Modern Heterocyclic Chemistry

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The replacement of a carbon atom by a heteroatom in a seven-membered carbocycle leads to the corresponding seven-membered heterocyclic ring system. Different types of heterocycles can be formed depending on the nature of the carbocycle. In a cycloheptatriene the replacement can involve any of the six sp 2 hybridized carbons or the sp 3 carbon atom, whereas in cycloheptane all carbon atoms are equivalent and replacement affords exclusively the fully saturated heterocyclic systems. Partially saturated seven-membered heterocycles can be viewed as derivatives or related systems of these two main seven-membered heterocyclic units arising from carbon replacement in cycloheptatriene and in cycloheptane. Replacement of the sp 3 hybridized carbon atom in cycloheptatriene by a nitrogen leads to an azacycloheptatriene known as 1H-azepine (1) and the corresponding 2H-, 3H-, and 4H-azepines (2-4) are the tautomeric forms generated by the replacement of the sp 2 carbons. 1H-Azepine is an unstable red oil that is prone to rearrange to the also unstable 3H-azepine in the presence of acids and bases. However, this tautomer seems to be more stable than both 4H-and 2H-azepine. The structures related to 1H-azepine that bear an oxygen or sulfur atom are known as oxepine (5) and thiepine (6) (thiepin is favored by Chemical Abstracts Service). Oxepine is much more stable than thiepine and has been synthesized, isolated, and characterized at room temperature while thiepine has not been detected to date. Stable monocyclic thiepines were prepared and characterized in the 1980s. Azepines, oxepines, and thiepines that are constrained to planar or almost planar conformations should be antiaromatic molecules with negative resonance energy and, as a consequence, these compounds are unknown.The fully saturated seven-membered heterocycle containing one nitrogen is azepane (7) (hexahydroazepine or perhydroazepine); the oxygen and sulfur analogues are known as oxepane (8) and thiepane (9). All of these compounds are stable and show typical behavior of secondary amine, ether and thioether, respectively. TwoModern Heterocyclic Chemistry, First Edition. Edited

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Section: Reactivity Of Oxepinesmentioning

confidence: 99%

Section: Tetrahydrooxepinesmentioning

confidence: 99%

“…N-Substituted 1H-azepines are oils or stable solids with well-defined melting points. Azepane (7) was first obtained in 1963 and is a typical secondary amine with a pK a of 11.29 [59].…”

Section: Relevant Natural and Useful Compoundsmentioning

confidence: 99%