Acylierung von Aminosäuren mit<i>pHT</i>‐Methoxybenzyloxycarbonyl‐azid

Weygand, F.; Hunger, Klaus

doi:10.1002/cber.19620950105

Cited by 106 publications

(28 citation statements)

References 11 publications

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“…Z-Ala-NHNHCHO Z-Ala-NHNH 2 (100 mg, 0.42 mmol) was dissolved in formic acid (2 ml) and the solution was kept at 20°C for 3 h. The formic acid was removed in vacuo and the residue was recrystallized from CH 3 Treatment of Z-Ala-NHNHCHO with Hydrazine Hydrate Z-Ala-NHNHCHO (100 mg, 0.38 mmol) was dissolved in a mixture of CH 3 CN and H 2 O (1/1, 3 ml). Hydrazine hydrate (10 eq) [or hydrazine hydrate (10 eq)ϩAcOH (10 eq)] was added to the solution and the entire mixture was stirred at 20°C (or 50°C).…”

Section: Methodsmentioning

confidence: 99%

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Acylation of Hydrazides with Acetic Acid and Formic Acid.

Hojo

Maeda

Smith

et al. 2002

CHEMICAL & PHARMACEUTICAL BULLETIN

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Amino acid hydrazides are important intermediates for peptide synthesis by the azide coupling method. An N-protected amino acid hydrazide is converted to a corresponding azide, followed by a coupling reaction with an amino group of an amino acid to form a peptide bond. Hydrazides are also important in a Curtius rearrangement reaction as starting material for the azide. The conversion of a hydrazide to an azide is performed with a nitrite (sodium nitrite, amyl nitrite, tertbutyl nitrite, etc.) in the presence of an acid.1) Usually, hydrochloric acid is used as the acid, but organic acids are often used. Hydrazides are also important starting materials for the preparation of N-protected amino acid derivatives. tert-Butyloxycarbonyl (Boc) and p-methoxybenzyloxycarbonyl [Z(OMe)] amino acids were prepared by the reaction of an amino acid with the corresponding azide (Boc-N 3 or Z(OMe)-N 3 ). These azides were prepared from the corresponding hydrazides (Boc-NHNH 2 or Z(OMe)-NHNH 2 ) with sodium nitrite in aqueous acetic acid. Boc-N 32) was prepared in 43% acetic acid and Z(OMe)-N 33) was prepared in 45% acetic acid from each corresponding hydrazide.Since acetic acid and formic acid have superior solubility, they are often used as both an acid and a solvent when an azide is prepared from a hydrazide with a nitrite. In these cases, especially when formic acid was used, we occasionally observed that the yield of the azide coupling reaction was poor. We speculated that the poor yield was caused by acylation on the hydrazide with the corresponding acid. The acylated hydrazide could not be converted to the azide and, as a result, the coupling yield of the azide reaction was poor. We examined acylation on a hydrazide by treatment with acetic acid and formic acid. Benzyloxycarbonylalanine hydrazide (Z-Ala-NHNH 2 ) was treated with acetic acid and the reaction mixture was examined by HPLC.As shown in Fig. 1, a new peak was observed after treatment with acetic acid at 20°C. Analysis of mass and NMR spectra revealed that the new peak corresponded to the acetyl derivative. After 1 and 12 h at 20°C, 11 and 49% of the hydrazide was acetylated, respectively. We examined acetylation with various concentrations of acetic acid and the results are shown in Fig. 2.The rate of acetylation was dependent upon the concentration of acetic acid. Even in aqueous 10% acetic acid, 3% of the hydrazide was acetylated after 1 h.Next, formylation of the hydrazide with formic acid was examined. As shown in Fig. 3, a new peak was observed after treatment with formic acid. The new peak was isolated and identified as the formyl derivative by time of flight mass spectra (TOF-MS) and NMR spectral analysis. After 20 min, 60% of the hydrazide was formylated. Formylation was examined at various concentrations of formic acid and the re- * To whom correspondence should be addressed. In peptide synthesis, hydrazides are important intermediates for the azide coupling method. A hydrazide is converted to the corresponding azide in the presence of an acid and a nitr...

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Section: Methodsmentioning

confidence: 99%

“…These azides were prepared from the corresponding hydrazides (Boc-NHNH 2 or Z(OMe)-NHNH 2 ) with sodium nitrite in aqueous acetic acid. Boc-N 3 2) was prepared in 43% acetic acid and Z(OMe)-N 3 3) was prepared in 45% acetic acid from each corresponding hydrazide.…”

mentioning

confidence: 99%

Acylation of Hydrazides with Acetic Acid and Formic Acid.

Hojo

Maeda

Smith

et al. 2002

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…The Z (23) group can also be removed by acidolysis, but strong acids, such as HBr in HOAc, are required, [168]. Substituted derivatives of the Z (23) group are also used in solution synthesis as N -protecting groups that are more acid labile such as the 2-(4-biphenylyl)isopropoxycarbonyl (Bpoc, 62) [169]; the 4-methoxy-benzyloxycarbonyl (Moz, 63) [170], which can be removed by TFA; and the α,α-dimethyl-3,5-dimethoxybenzyloxy (Ddz, 64) group [171], which can be removed by photolysis [172]. A less common N -protecting group in solution peptide synthesis is the 2,2,2-trichloroethoxycarbonyl (Troc, 65)-groups [173], which is removed under treatment with Zn in HOAc [174].…”

Section: N Protection Of the N-terminal Amino Acid Derivative Or Fragmentioning

confidence: 99%

Methods for the Peptide Synthesis and Analysis

Tulla‐Puche

El‐Faham

Galanis

et al. 2015

Peptide Chemistry and Drug Design

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“…3,4-Di-0-acetyl-D-xylal (14g) (27) was dissolved in carbon tetrachloride and treated with chlorine (2,5). The mixture of epimeric mono-chloro-pentoses was then obtained using methods described by Vargha and Kuszmann (7).…”

Section: Independent Synthesis Of 2-chloro-2-deoxy-d-lyxose (6)mentioning

confidence: 99%

Stereospecific synthesis of two epimeric 2-chlorodeoxy pentoses involving anomeric chlorine participation

Jennings¹

1970

Can. J. Chem.

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A simple procedure has been developed for the stereospecific synthesis of some 2-chloro-2-deoxy pentoses. Treatment of P-D-xylopyranosyl chloride 2,3,4-tri(ch1orosulfate) with aluminum chloride (> 1 mole equivalent) resulted in specific chloro-displacement of the C-2 chlorosulfate group via a mechanism involving anomeric chlorine migration, which occurred to the extent of almost 100%. The resultant crystalline 2-chloro-2-deoxy-a-D-lyxopyranosyl chloride 3,4-di(chlorosulfate) when treated with sodium iodide yielded crystalline 2-chloro-2-deoxy-D-lyxose. Similarly a-D-lyxpoyranosyl chloride 2,3,4-tri(chlorosulfate) yielded 2-chloro-2-deoxy-a-D-xylopyranosyl chloride 3,4-di(chlorosulfate) from which pure 2-chloro-2-deoxy-D-xylose was obtained by a modified procedure. The structures of these compounds have been confirmed and the mechanism is discussed.

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Acylierung von Aminosäuren mitpHT‐Methoxybenzyloxycarbonyl‐azid

Cited by 106 publications

References 11 publications

Acylation of Hydrazides with Acetic Acid and Formic Acid.

Acylation of Hydrazides with Acetic Acid and Formic Acid.

Methods for the Peptide Synthesis and Analysis

Stereospecific synthesis of two epimeric 2-chlorodeoxy pentoses involving anomeric chlorine participation

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