On the Selective<i>N</i>-Methylation of BOC-Protected Amino Acids

Malkov, Andrei V.; Vranková, Kvetoslava; Černý, M.; Kočovský, Pavel

doi:10.1021/jo9016293

Cited by 40 publications

(38 citation statements)

References 28 publications

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“…The four stereoisomers of NMeIle were synthesized according to the literature. 28,29 On the basis of these standards, the absolute configuration of NMeIle was determined to be l (2 S , 3 S ). The 2 S , 3 R and 2 S , 3 S isomers of 3-hydroxyleucine were synthesized following Bonnard’s procedure 16 and were derivatized with l - and d -FDLA respectively.…”

Section: Resultsmentioning

confidence: 99%

“…28 The methylation of N Boc- l -Ile was carried out using Malkov’s method. 29 The Boc-protected NMeIle was subjected to acid hydrolysis using the general peptide hydrolysis scheme as described below, to yield l - N -methylisoleucine (73.11 mg), which was analyzed by the advanced Marfey’s method. Although citric acid from the workup was observed as a minor impurity in the 1 H NMR spectrum of l - N -methylisoleucine, it did not interfere with the advanced Marfey’s analysis.…”

Section: Methodsmentioning

confidence: 99%

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Trichormamides A and B with Antiproliferative Activity from the Cultured Freshwater Cyanobacterium Trichormus sp. UIC 10339

et al. 2014

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Two new cyclic lipopeptides, trichormamides A (1) and B (2), were isolated from the cultured freshwater cyanobacterium Trichormus sp. UIC 10339. The strain was obtained from a sample collected in Raven Lake in Northern Wisconsin. The planar structures of trichormamides A (1) and B (2) were determined using a combination of spectroscopic analyses including HRESIMS and 1D and 2D NMR experiments. The absolute configurations of the amino acid residues were assigned by the advanced Marfey’s method after acid hydrolysis. Trichormamide A (1) is a cyclic undecapeptide containing two d-amino acid residues (d-Tyr and d-Leu) and one β-amino acid residue (β-aminodecanoic acid). Trichormamide B (2) is a cyclic dodecapeptide characterized by the presence of four nonstandard α-amino acid residues (homoserine, N-methylisoleucine, and two 3-hydroxyleucines) and one β-amino acid residue (β-aminodecanoic acid). Trichormamide B (2) was cytotoxic against MDA-MB-435 and HT-29 cancer cell lines with IC50 values of 0.8 and 1.5 μM, respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Trichormamides A and B with Antiproliferative Activity from the Cultured Freshwater Cyanobacterium Trichormus sp. UIC 10339

et al. 2014

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“…2‐(N‐(tert‐butoxycarbonyl)amino)‐alanine was methylated using iodomethane and sodium hydride following the method described by Malkov et al 2‐(N‐(tert‐butoxycarbonyl)amino)‐alanine (1.9 g) was stirred in THF (20 mL) on an ice bath under inert conditions to which a 10 molar equivalent of methyl iodide was added in one addition. To this, a 10 molar equivalent of sodium hydride 60% dispersion mineral oil was slowly added and the mixture left to stir at room temperature for 24 hours.…”

Section: Methodsmentioning

confidence: 99%

“…The product was examined by gas chromatography-mass spectrometry (GC-MS) and proton nuclear magnetic resonance ( 1 H NMR) and its identity confirmed as 2-(N-(tert-butoxycarbonyl)amino)-alanine (1.9 g) by comparison to literature. 8 Step 2: Synthesis of N-(tert-butoxycarbonyl)-N-methylalanine 2-(N-(tert-butoxycarbonyl)amino)-alanine was methylated using iodomethane and sodium hydride following the method described by Malkov et al 9 2-(N-(tert-butoxycarbonyl)amino)-alanine (1.9 g) was stirred in THF (20 mL) on an ice bath under inert conditions to which a 10 molar equivalent of methyl iodide was added in one addition.…”

Section: 21 | Synthesis Of N-methylalaninementioning

confidence: 99%

Profiling ephedrine prepared from N‐methylalanine via the Akabori‐Momotani reaction

Doddridge

Collins

Salouros

2017

Drug Testing and Analysis

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Novel methods for synthesising methylamphetamine precursors are appearing in clandestine laboratories within Australia. One such laboratory involved the synthesis of ephedrine from N-methylalanine and benzaldehyde via the Akabori-Momotani reaction. This article presents chiral and stable isotope ratios of ephedrine synthesised via this method, along with a chemical profile of methylamphetamine produced from this ephedrine. Based on the chiral results and the δ C, δ N, and δ H values, it is possible to distinguish ephedrine made via the Akabori-Momotani reaction from ephedrine of a "natural", "semi-synthetic", or "fully-synthetic" origin. Methylamphetamine and ephedrine samples synthesised from benzaldehyde having an enriched δ H value (ie, > 0‰), via the Akabori-Momotani reaction, had an isotopic profile which set them apart from all other methylamphetamine samples. It was noted, however, that using stable isotope ratios alone to determine the precursor of methylamphetamine is limited; they could not with confidence differentiate between methylamphetamine and ephedrine synthesised from benzaldehyde having a depleted δ H value (ie, <0‰) from other ephedrine sources and phenyl-2-propanone based methylamphetamine samples profiled.

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“…For the synthesis of the heterocycle-based fragments C (Scheme 3), we started with commercially available Boc- l -Val-OH, which was easily converted to the known [35,36] amide 16 . Careful amide dehydration by means of cyanuric chloride in DMF afforded the corresponding nitrile 17 , avoiding possible racemisation [37].…”

Section: Resultsmentioning

confidence: 99%

Hemiasterlin analogues incorporating an aromatic, and heterocyclic type C-terminus: design, synthesis and biological evaluation

et al. 2014

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A representative series of structural analogs of the antimitotic tripeptides hemiasterlins have been designed and synthesized, as potential inhibitors of tubulin polymerization. Relying also on a computational approach, we aimed to explore unknown extensive changes at the C-fragment, by incorporating the conformationally required double bond into five- and six-membered rings. Key steps of the synthetic strategy are a dynamic resolution affording the A-fragment in 97 % ee and the preparation of six new cyclic C fragments, all potentially able to interact with tubulin by means of H bonds. Unexpectedly, biological evaluation of these analogs did not provide evidences neither for cytotoxic effect nor for inhibition of tubulin polymerization.

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On the SelectiveN-Methylation of BOC-Protected Amino Acids

Cited by 40 publications

References 28 publications

Trichormamides A and B with Antiproliferative Activity from the Cultured Freshwater Cyanobacterium Trichormus sp. UIC 10339

Trichormamides A and B with Antiproliferative Activity from the Cultured Freshwater Cyanobacterium Trichormus sp. UIC 10339

Profiling ephedrine prepared from N‐methylalanine via the Akabori‐Momotani reaction

Hemiasterlin analogues incorporating an aromatic, and heterocyclic type C-terminus: design, synthesis and biological evaluation

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