Azomethine Imines in Four‐ and Five‐Membered Rings: Stable Cyclic Valence Isomers of an
            <i>α</i>
            ‐(Phenyldiazenyl)ketocarbene

Schantl, J. G.; Rettenbacher, Arno S.; Wurst, Klaus

doi:10.1002/(sici)1521-3773(19980904)37:16<2229::aid-anie2229>3.0.co;2-#

Cited by 7 publications

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[3 + 2] Cycloadditions of Azomethine Imines

Grošelj

Svete

2020

Organic Reactions

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In spite of their late discovery in the middle of 20 th century, the importance of azomethine imines and their [3+2] cycloaddition reactions has grown constantly throughout the decades. Today, [3+2] cycloadditions of azomethine imines have become indispensable in the preparation of pyrazole derivatives with all degrees of saturation. The structural diversity of azomethine imines is wide and comprises acyclic, C , N ‐cyclic, N , N ‐cyclic, and C , N , N ‐cyclic 1,3‐dipoles. Although electron‐deficient dipolarophiles are preferred, electron‐rich dipolarophiles, such as enol ethers and enamines, are also commonly used in these reactions. Compared to cyclocondensation methods and [3+2] cycloadditions with diazoalkanes and nitrile imines, [3+2] cycloadditions with azomethine imines provide access to a greater diversity of pyrazole derivatives with all degrees of saturation. As with other 1,3‐dipolar cycloadditions, a concerted and nearly synchronous mechanism has been proposed for most [3+2] cycloadditions of azomethine imines, although a stepwise mechanism may be viable in some cases. Several examples of asymmetric [3+2] cycloadditions of azomethine imines that afford non‐racemic cycloadducts with high enantioselectivity have been reported. These asymmetric cycloadditions are performed with various types of transition metal catalysts and organocatalysts, and indicate their potential for the asymmetric synthesis of saturated pyrazole derivatives. Finally, many examples of copper‐catalyzed and thermal, strain‐promoted [3+2] cycloadditions of azomethine imines (in particular sydnones) clearly indicate wide applicability of these reactions in bioconjugation, fluorescent labelling, materials functionalization, and other applications outside the realm of pure organic synthesis.

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[3 + 2] Cycloadditions of Azomethine Imines

Grošelj

Svete

2020

Organic Reactions

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ChemInform Abstract: Azomethine Imines in Four‐ and Five‐Membered Rings: Stable Cyclic Valence Isomers of an α‐(Phenyldiazenyl)ketocarbene.

1999

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Azomethine Imines in Four-and Five-Membered Rings: Stable Cyclic Valence Isomers of an α-(Phenyldiazenyl)ketocarbene.-The title compound (IV) represents a novel class of four-membered-ring azomethine imines with an exocyclic nitrogen atom. The imine (V) is the first example of a carba-sydnone in which the ring oxygen is replaced by a tetrahedral carbon atom. Treatment of the diazoketone (III) with Newman's reagent in MeOH leads to (IV) and the ester (VII) via an expected Wolff rearrangement. -(SCHANTL, J. G.; RETTENBACHER, A. S.; WURST, K.; Angew.

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The crystal structure of 9‐chloro‐4,5‐dihydro‐2‐ethyl‐1‐(2,4,6‐trichlorophenyl)‐1H‐1,2,4‐triazolo[3,2‐d][1,5]‐benzoxazepinium hexachloroantimonate

Liu

Ding

et al. 2000

Journal of Heterocyclic Chem

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The title compound 4, i.e. 9‐chloro‐4,5‐dihydro‐2‐ethyl‐1‐(2,4,6‐trichlorophenyl)‐1H‐1,2,4‐triazolo[3,2‐d]‐[1,5]benzoxazepinium hexachloroantimonate, is a novel 6‐7‐5 tricyclic heterocycle. C18H14Cl4N3O·SbCJ6, M = 764.61, P21/c(#14), a = 13.457(4), b = 11.583(2), c = 18.992(3) Å α = 90, β = 110.11(1)°, Z = 4, V = 2780(1) Å3, Dc = 1.827 g/cc, μ (MoKα) = 19.69 cm−1, F(000) = 1488.00, T = 293 K, Rint = 0.055 for 3094 independent reflections with I>3.00σ(I). The five‐membered heterocyclic ring is nearly planar, with the trichlorophenyl ring at N(2) almost perpendicular to it. However, the seven‐membered ring is not planar, but adopts a twist‐boat conformation.

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Azomethine Imines in Four‐ and Five‐Membered Rings: Stable Cyclic Valence Isomers of an α ‐(Phenyldiazenyl)ketocarbene

Cited by 7 publications

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[3 + 2] Cycloadditions of Azomethine Imines

[3 + 2] Cycloadditions of Azomethine Imines

ChemInform Abstract: Azomethine Imines in Four‐ and Five‐Membered Rings: Stable Cyclic Valence Isomers of an α‐(Phenyldiazenyl)ketocarbene.

The crystal structure of 9‐chloro‐4,5‐dihydro‐2‐ethyl‐1‐(2,4,6‐trichlorophenyl)‐1H‐1,2,4‐triazolo[3,2‐d][1,5]‐benzoxazepinium hexachloroantimonate

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