Synthese von ?-Azidozimts�ureestern

Hemetsberger, H.; Knittel, D.; Weidmann, Hans

doi:10.1007/bf00900176

Cited by 79 publications

(27 citation statements)

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“…Ethyl E-2-azido-3-phenylpropenoate 7 (prepared by the procedure of Hermtsberger 15 with the Rees modification 16 ) with triflic acid in dicloromethane at 0 °C gave the 1H-indole 4 in 45% yield, mp 124-125 °C, while the TFA-catalyzed reaction under the same conditions gave 4 in 52% yield. Decomposition with AlCl 3 gave the 1H-indole 4 in 29% yield.…”

Section: Resultsmentioning

confidence: 99%

Reaction of aromatic azides with strong acids: formation of fused nitrogen heterocycles and arylamines

Carvalho¹,

Sorrilha²,

Rodrigues³

1999

J. Braz. Chem. Soc.

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Descrevemos neste trabalho a ação de ácido trifluoroacético, ácido trifluorometanossulfônico e cloreto de alumínio sobre aril azidas orto-substituídas para formar indóis, azepinas e arilaminas com bons rendimentos. As azidas protonadas perdem nitrogênio para formar íons arilnitrênios intermediários que sofrem N-substituição aromática intramolecular. A decomposição ácida de aril azidas é comparada com resultados de termólise tomados da literatura.We describe in this paper the action of trifluoroacetic acid, trifluoromethanesulfonic acid and aluminum chloride upon ortho-substituted aryl azides to form indoles, azepines and arylamines in good yields. The protonated azides lose nitrogen to form arylnitrenium ion intermediates which undergo intramolecular aromatic N-substitution. The acid decomposition of aryl azides is compared with reported thermolyses.

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Section: Resultsmentioning

confidence: 99%

Reaction of aromatic azides with strong acids: formation of fused nitrogen heterocycles and arylamines

Carvalho¹,

Sorrilha²,

Rodrigues³

1999

J. Braz. Chem. Soc.

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“…2 Very littlework has been reported concerning the interception of the reaction to allow isolation of these hydroxyazides, 3 and our synthetic studies commenced here. Thus, reaction of benzaldehyde with ethylazidoacetate in the presence of one equivalent of sodium ethoxide in ethanol at room temperature overnight gave, as expected, a good yield of azidocinnamate (1a).…”

Section: Methodsmentioning

confidence: 99%

Reactions of Azidoacetate Enolates with Aromatic Aldehydes: Preparation of N-BOC 3-Arylserines

Geen¹,

Shaw²,

Sweeney³

1999

Synlett

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Azidoacetates undergo aldol-like reaction with aromaticaldehydes in the presence of sub-stoichiometric amounts of NaOEt. Theproduct azido alcohols (2a)-(2q) may be directly converted to N-BOC phenyl serine analogues Keywords: aminoacids, arylserines As part of a program of research concerning incorporation of non-proteinogenic aminoacids into polypeptides, we required a new entry to a range of 2-amino-3-hydroxyesters. 1 We thought that such compounds would be available from the corresponding azidoalcohols, and that if such compounds could be prepared via an aldol-like reaction, this would represent a useful addition to the armoury of synthetic chemistry. We here report the preliminary results wehave obtained from study of such reactions. Scheme 1The reaction of aryl aldehydes with ethylazidoacetate is well-known to give good yields of 2-azidocinnamates (1), through the intermediacy of hydroxyazide (2) (Scheme 1), the reaction forming the basis of the Hemetsberger-Knittelsynthesis of indoles. 2 Very littlework has been reported concerning the interception of the reaction to allow isolation of these hydroxyazides, 3 and our synthetic studies commenced here. Thus, reaction of benzaldehyde with ethylazidoacetate in the presence of one equivalent of sodium ethoxide in ethanol at room temperature overnight gave, as expected, a good yield of azidocinnamate (1a). We then repeated the reaction at low temperature, this time using a hindered base (LDA) and an aprotic solvent (THF): we isolated only starting materials from the reaction. Using a variety of strong bases, a similar lack of success was observed. When the original, protic reaction was repeated using a sub-stoichiometric amountof base (0.1eq.), rather than a full equivalent, no azidocinnamate was observed and hydroxyazide (2a) was isolated as the only product of the reaction, in 46% yield (Scheme2). This observation is at odds with that previously described, which concluded that azidoalcohols could only be obtained from such reactions when reaction temperatures were considerably lower than ambient (ca. -40°C). 3 Thus, (2a) was obtained as a 2:1 mixture of diastereoisomers, in favour of the syn-isomer (as judged from analysis of 1 H nmr data); 4 the isomers were not separable using standard column chromatography.When (2a) was resubjected to the dipolar, aprotic reaction conditions previously examined, (LHMDS base, THF solvent,-78°C), retro-aldol reaction occurred and only ethyl azidoacetate andbenzaldehyde were isolated from the re- Table 1 Preparation of 2-Azido-3-Hydroxyesters via Azidoaldol reaction Downloaded by: UC Santa Barbara. Copyrighted material.

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“…Synthesis of N-benzoyl-N-[2-(6-methoxymethoxy-2-vinyl-1H-indol-3-yl)ethyl]amine (2). The right indole 2 was synthesized by the Weidmann procedure [8], by cyclization of the azide compound 11. Thus, 4-(methoxymethoxy)benzaldehyde (10) [9] was coupled with azidoacetate under strongly basic condition to give azide 11 in 74% yield.…”

Section: Synthesis Of 67-dimethoxy-5-methoxymethoxy-1h-indole (1)mentioning

confidence: 99%