New thermal rearrangement of 2H-azirines: Formation of enamines and their cyclization into pyridines

1. Einleitung. -Die Chemie der 2H-Azirine ist eingehend untersucht und in zahlreichen Arbeiten beschrieben worden (obersichtsartikel [ 1-41; fur neuere Arbeiten siehe [5-121 und dort zit. Lit.). Die leichte Zuganglichkeit dieses gespannten Stickstoffdreiringes (vgl. z. B. [ 13-16]), sowie die Moglichkeit, unter geeigneten Reaktionsbedingungen jede der drei Ringbindungen selektiv zu spalten, machen 2 H-Azirine zu wertvollen Synthesebausteinen fur N-haltige Verbindungen. Theoretische Untersuchungen [ 171 sowie Rontgenkristallstrukturanalysen an freien Azirinen [ 181 oder an deren Ubergangsmetallkomplexen [ 191 geben die Struktur dieser Verbindungen wieder und machen die verschiedenen aufgefundenen Reaktionsweisen verstandlich. Die 2H-Azirine vom Typ l a , mit einem Alkyl-oder Arylrest in 3-Stellung, besitzen ein Dreiring-Iminsystem als die die Reaktionsweise bestimmende Funktio-R5

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“…C);37,4 und 33,6 (br. Signale,CH3N);26,l (CH3CH2);9,9 (CH3CH2). Das Signal von C(2) ist nicht zu erkennen.…”

Section: Synihese Von 2-athyl-3-(n-methylanilino)-2-phenyl-2h-azirinunclassified

Photochemisch induzierte Reaktionen von 3‐Amino‐2H‐azirinen

Dietliker

Heimgartner

1983

Helvetica Chimica Acta

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“…Indole-3-carbaldehydes are considerably less reactive than, for instance, benzaldehyde, and therefore it was expected that condensation of these aldehydes with ethyl azidoacetate might be difficult. This was indeed the case, and only poor to moderate yields of the required azidoacrylates (6) were obtained from the aldehydes (5) by condensation with ethyl azidoacetate under the standard condition^.^ N-Unsubstituted indole-3-carbaldehydes did not condense with ethyl azidoacetate and it would also appear that the reaction is sensitive to steric effects since the yields of the azides (6) decrease markedly as the size of the 2-substitutent increases. Similar effects have been noted previously, 2-methylindole-3-carbaldehyde being considerably less reactive towards condensation with malonic acid than the 2-unsubstituted a l d e h ~d e .…”

Section: Resultsmentioning

confidence: 99%

[2,3] Fused indoles. Synthesis of β-carbolines and azepino[4,5-b]indoles from 3-(2-alkylindol-3-yl)-2-azidoacrylates¹

Moody¹,

Ward²

1984

J. Chem. Soc., Perkin Trans. 1

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Decomposition of the azidoacrylates (6) derived from 2-substituted indole-3-carbaldehydes gives pharmacologically important p-carbolines [( 8), (1 l ) ] , azepino[4,5-6]indoles (1 3), or enamines (14) depending on the conditions. The formation of azepinoindoles, shown to proceed by cyclisation of the initially formed enamines, represents a new reaction of vinyl azides which is particularly favoured in the indole series.

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ChemInform Abstract: NEW THERMAL REARRANGEMENT OF 2H‐AZIRINES: FORMATION OF ENAMINES AND THEIR CYCLIZATION INTO PYRIDINES

Isomura¹,

Noguchi²,

Saruwatari³

et al. 1981

Chemischer Informationsdienst

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New thermal rearrangement of 2H-azirines: Formation of enamines and their cyclization into pyridines

Cited by 7 publications

References 5 publications

Photochemisch induzierte Reaktionen von 3‐Amino‐2H‐azirinen

Photochemisch induzierte Reaktionen von 3‐Amino‐2H‐azirinen

[2,3] Fused indoles. Synthesis of β-carbolines and azepino[4,5-b]indoles from 3-(2-alkylindol-3-yl)-2-azidoacrylates¹

ChemInform Abstract: NEW THERMAL REARRANGEMENT OF 2H‐AZIRINES: FORMATION OF ENAMINES AND THEIR CYCLIZATION INTO PYRIDINES

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New thermal rearrangement of 2H-azirines: Formation of enamines and their cyclization into pyridines

Cited by 7 publications

References 5 publications

Photochemisch induzierte Reaktionen von 3‐Amino‐2H‐azirinen

Photochemisch induzierte Reaktionen von 3‐Amino‐2H‐azirinen

[2,3] Fused indoles. Synthesis of β-carbolines and azepino[4,5-b]indoles from 3-(2-alkylindol-3-yl)-2-azidoacrylates1

ChemInform Abstract: NEW THERMAL REARRANGEMENT OF 2H‐AZIRINES: FORMATION OF ENAMINES AND THEIR CYCLIZATION INTO PYRIDINES

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[2,3] Fused indoles. Synthesis of β-carbolines and azepino[4,5-b]indoles from 3-(2-alkylindol-3-yl)-2-azidoacrylates¹