Reaction of 3-unsubstituted N-arylisoxazolium salts with carboxylic acid anions

Woodward, R. B.; Woodman, D. J.; Kobayashi, Yoshiro

doi:10.1021/jo01288a028

Cited by 18 publications

(6 citation statements)

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“…-Im Vergleich zu Inaminen reagieren die cdnamin-carbonylsysteme>> 1 bei der Peptidsynthese sehr vie1 selektiver und weitgehend racemisierungsfrei, wahrend verschiedene Folge-und Nebenreaktionen sowohl der Inamine wie der daraus bereiteten Enolester [28] [30] nicht beobachtet werden. Bei der Peptidsynthese iiber Isoxazoliumsalze von Woodward & Woodman [3 11 entstehen N-monosubstituierte 3-Acyloxy-acrylamide des Typs 5, deren Amidfunktion Nebenreaktionen eingehen kann [32]. Dies ist bei den aus ((Push-Pull ))-Acetylenen 1 bereiteten Enolestern 5, welche eine Dialkylamidfunktion tragen, nicht moglich.…”

Section: Diskussion Undunclassified

«Push‐Pull»‐Acetylene als Hilfsmittel zur Synthese von Peptiden

Neuenschwander

Fahrni

Lienhard

1978

Helvetica Chimica Acta

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Push-pull'-acetylenes 1 are excellent reagents for peptide synthesis: Addition of 'push-pull'-acetylenes to solutions of N-protected amino acids (or vice versa) gives enol esters 5, which react selectively with the amino function of a second amino acid. In this way serine, tyrosine, 4-hydroxyproline, cysteine as well as histidine are linked to form dipeptide esters without protection of the second functional group (OH, SH or NH). The amount of racemization is very low. Similarly tri-as well as tetrapeptides are available. The versatility of the reaction is discussed. Einleitung. -ccPush-Pull))-Acetylene 1 [5][6] setzen sich mit Carbonsauren unter schonenden Bedingungen annahernd quantitativ zu 3-Acyloxy-acrylamiden (2) urn [ 11 [5] [7] (Schema 1). Da die Addition der Carboxylgruppe sehr selektiv verlauft [ 11, sind auch Carbonsauren, die weitere funktionelle Gruppen tragen [2] [8], zur Re-

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Section: Diskussion Undunclassified

«Push‐Pull»‐Acetylene als Hilfsmittel zur Synthese von Peptiden

Neuenschwander

Fahrni

Lienhard

1978

Helvetica Chimica Acta

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“…Dimethyl (1,1,2-Trimethylallyl)succinate (2).-The liquid compound was further purified by preparative glpc (3 ft X 0.25 in. 10% silicone rubber SE-30 on Chromosorb P, 130°): ir (film) 3080, 1735, and 895 cm-1; nmr (60 MHz) 5 1.05 and 1.08 (2s, 6), 1.77 (br s, 3), 2.03-3.05 (m, 3), 3.60 and 3.63 (2s, 6), and 4.76 (br s, 2); mass spectrum m/e (rel intensity) 228.139 (M+, 3, caled for Ci2H2C04 228.135), 83 (100).…”

Section: Experimental Section10mentioning

confidence: 99%

“…Dimethyl (2,3-Dimethyl-2-butenyl)succinate (3).-The liquid compound was further purified by preparative glpc (conditions as for 2, above): ir 1740 cm"1; nmr (60 MHz) 5 1.63 (s, 9), 2.12-2.67 (m, 4), 2.72-3.17 (m, 1), and 3.62 (s, 6); mass spectrum m/e (rel intensity) 228.124 (M+, 28, caled for Ci2H2o04 228.135), 83 (100).…”

Section: Experimental Section10mentioning

confidence: 99%

“…since maléate and fumarate esters are rapidly interconverted under the reaction conditions and both are present in the reaction mixture, it made no difference whether maleate or fumarate esters were used as starting material. 3 It remained to prove the stereochemistry of the isomer of 1 produced in the photochemical reaction and to prepare the other isomer, if possible. There are four classical methods for determining the stereochemistry of a vicinally disubstituted cyclic compound.…”

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confidence: 99%

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Photochemical addition of dimethyl maleate to 2,3-dimethyl-2-butene. Use of a chiral shift reagent

Goe¹

1973

J. Org. Chem.

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“…and four products have been isolated in varying amounts for the reaction of (13; R = Ph) with benzylamine . 17 The key finding is therefore the progressive elimination of the competing intramolecular rearrangement of (10) to (12) when the bulk of R is increased. This is an obvious advantage in peptide synthesis where the desired reaction involves acyl transfer from (9) to an external nucleophile.…”

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confidence: 99%

Formation, rearrangement, and hydrolysis of enol esters derived from isoxazolium salts

Hegarty¹,

Tuohey²

1980

J. Chem. Soc., Perkin Trans. 2

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The hydration of N-t-butylbenzoylketenimine (2c) in water at 25" [to give the amide (7c)] occurs via acid-catalysed (at pH < 6) and pH-independent pathways. General acid catalysis by acetic acid is noted leading to the enol esters (3). The further reactions of these esters (3 ; R = Me, Et, or But) in aqueous solution have been investigated. In basic solution (pH > 6) (3; R1 = Me or Et) undergo HO--catalysed neighbouring amide group participation to give the N-acyl analogues (5), which are subsequently hydrolysed to the amides (7) at a rate which can be slower or faster than the rate of formation of (5). However when R = But, no 0 + N acyl group rearrangement is observed [i.e. (3c) -+ (5c)l ; instead slow base-catalysed hydrolysis of the enol ester occurs to give (7c) directly. In acid solution all the enol esters studied are hydrolysed at much the same rate. The implications of these results for the use of the isoxazolium salts (1) [the precursors of the enol esters (3)] as reagents for peptide synthesis are commented on.

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Reaction of 3-unsubstituted N-arylisoxazolium salts with carboxylic acid anions

Cited by 18 publications

References 0 publications

«Push‐Pull»‐Acetylene als Hilfsmittel zur Synthese von Peptiden

«Push‐Pull»‐Acetylene als Hilfsmittel zur Synthese von Peptiden

Photochemical addition of dimethyl maleate to 2,3-dimethyl-2-butene. Use of a chiral shift reagent

Formation, rearrangement, and hydrolysis of enol esters derived from isoxazolium salts

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