Asymmetric synthesis of dideazafolate antitumor agents via amidomethylation of nonracemic oxazolidinone imidates. Synthesis of LY309887, a cytotoxic dideazafolate analog related to lometrexol

Barnett, Charles J.; Wilson, Thomas M.; Evans, David A.; Somers, T. C.

doi:10.1016/s0040-4039(96)02418-5

Cited by 24 publications

(17 citation statements)

References 9 publications

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“…Thus, this method can only be used to prepare a limited number of ␤-amino acids. Following improvements in this field with the introduction of amidomethylating agents bearing N-protecting groups that are cleavable under milder conditions by Wyatt and co-workers 167 and Evans and colleagues 168 (i.e., 1-(N-benzyloxycarbonylaminomethyl)benzotriazole and N-methoxymethyl benzyl carbamate, respectively), the synthesis of a wide range of ␤ 2 -amino acid SCHEME 19 Diastereoselective amidomethylation of chiral (a) N-acyl-sultam and (b) N-acyloxazolidinone derivatives.…”

Section: Diastereoselective Addition Of Chiral Enolates To Acyliminiumentioning

confidence: 99%

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β²‐amino acids—syntheses, occurrence in natural products, and components of β‐peptides^1,2

2004

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Although they are less abundant than their alpha-analogues, beta-amino acids occur in nature both in free form and bound to peptides. Oligomers composed exclusively of beta-amino acids (so-called beta-peptides) might be the most thoroughly investigated peptidomimetics. Beside the facts that they are stable to metabolism, exhibit slow microbial degradation, and are inherently stable to proteases and peptidases, they fold into well-ordered secondary structures consisting of helices, turns, and sheets. In this respect, the most intriguing effects have been observed when beta2-amino acids are present in the beta-peptide backbone. This review gives an overview of the occurrence and importance of beta2-amino acids in nature, placing emphasis on the metabolic pathways of beta-aminoisobutyric acid (beta-Aib) and the appearance of beta2-amino acids as secondary metabolites or as components of more complex natural products, such as peptides, depsipeptides, lactones, and alkaloids. In addition, a compilation of the syntheses of both achiral and chiral beta2-amino acids is presented. While there are numerous routes to achiral beta2-amino acids, their EPC synthesis is currently the subject of many investigations. These include the diastereoselective alkylation and Mannich-type reactions of cyclic- or acyclic beta-homoglycine derivatives containing chiral auxiliaries, the Curtius degradation, the employment of transition-metal catalyzed reactions such as enantioselective hydrogenations, reductions, C-H insertions, and Michael-type additions, and the resolution of rac. beta2-amino acids, as well as several miscellaneous methods. In the last part of the review, the importance of beta2-amino acids in the formation of beta-peptide secondary structures is discussed.

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Section: Diastereoselective Addition Of Chiral Enolates To Acyliminiumentioning

confidence: 99%

“…(a) According to Wyatt, 167,169 (b) with Evans' benzyl-oxazolidinone auxiliary, 168,170 and (c) with Seebach's oxazolidinone auxiliary.…”

Section: Scheme 21 Preparation Of ␤mentioning

confidence: 99%

β²‐amino acids—syntheses, occurrence in natural products, and components of β‐peptides^1,2

2004

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“…9, [15][16][17] At this point, the relative stereochemistry for aldol adduct 17 was determined after conversion to the the same lactone 12 prepared before (Scheme 4). [15][16][17] Formation of lactone Methylation of 17 with Me 3 OBF 4 in the presence of a proton sponge at ambient temperature, provided 19 in 60% isolated yield (Scheme 5).…”

Section: 12mentioning

confidence: 99%

“…[15][16][17] Formation of lactone Methylation of 17 with Me 3 OBF 4 in the presence of a proton sponge at ambient temperature, provided 19 in 60% isolated yield (Scheme 5). 16 As this reaction proved to be difficult to reproduce on a larger scale, we decided to promote the conversion of 17 to the corresponding primary alcohol.…”

Section: 12mentioning

confidence: 99%

Total synthesis of the potent immunosuppressant (-)-Pironetin

Dias¹,

Oliveira²,

Sousa³

et al. 2005

Arkivoc

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“…We set out to prepare a series of benzyl N-(alkoxymethyl)carbamates 3a -3d (Scheme 2) with the aim of comparing by-product formation in aminomethylation reactions. Benzyl N-(methoxymethyl)carbamate (3a) [34] and benzyl N-(isopropoxymethyl)carbamate (3b) [35] were included in our screen for completeness. As our third generation electrophiles, we chose benzyl N-[(2,2,2-trifluoroethoxy)methyl]carbamate (3c; because we envisaged that the 2,2,2-trifluoroethoxy leaving group would be less likely to act as a nucleophile) and benzyl N-[(benzyloxy)methyl]carbamate (3d; containing a BnO leaving group).…”

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confidence: 99%

Benzyl N‐[(Benzyloxy)methyl]carbamate: An Improved Aminomethylation Electrophile for the Synthesis of (Benzyloxy)carbonyl (Cbz)‐Protected Chiral β²‐Amino Acids

Brocklehurst

Furegati

Müller-Hartwieg

et al. 2010

Helvetica Chimica Acta

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a-Aminomethylation of (R)-DIOZ-alkylated (DIOZ ¼ 4-isopropyl-5,5-diphenyloxazolidin-2-one) substrates is a key step in the asymmetric synthesis of b 2 -amino acids, but it is unfortunately often accompanied by formation of transcarbamation by-products. Aminomethylation was tested using a range of electrophiles, and the amount of by-product formation was assessed in each case. Benzyl N-[(benzyloxy)methyl]carbamate electrophile 3d is unable to form this by-product due to its inherent benzyl substitution. Use of electrophile 3d showed an improved impurity profile in aminomethylation, thus leading to easier intermediate purification.

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Asymmetric synthesis of dideazafolate antitumor agents via amidomethylation of nonracemic oxazolidinone imidates. Synthesis of LY309887, a cytotoxic dideazafolate analog related to lometrexol

Cited by 24 publications

References 9 publications

β²‐amino acids—syntheses, occurrence in natural products, and components of β‐peptides^1,2

β²‐amino acids—syntheses, occurrence in natural products, and components of β‐peptides^1,2

Total synthesis of the potent immunosuppressant (-)-Pironetin

Benzyl N‐[(Benzyloxy)methyl]carbamate: An Improved Aminomethylation Electrophile for the Synthesis of (Benzyloxy)carbonyl (Cbz)‐Protected Chiral β²‐Amino Acids

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Asymmetric synthesis of dideazafolate antitumor agents via amidomethylation of nonracemic oxazolidinone imidates. Synthesis of LY309887, a cytotoxic dideazafolate analog related to lometrexol

Cited by 24 publications

References 9 publications

β2‐amino acids—syntheses, occurrence in natural products, and components of β‐peptides1,2

β2‐amino acids—syntheses, occurrence in natural products, and components of β‐peptides1,2

Total synthesis of the potent immunosuppressant (-)-Pironetin

Benzyl N‐[(Benzyloxy)methyl]carbamate: An Improved Aminomethylation Electrophile for the Synthesis of (Benzyloxy)carbonyl (Cbz)‐Protected Chiral β2‐Amino Acids

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Product

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β²‐amino acids—syntheses, occurrence in natural products, and components of β‐peptides^1,2

β²‐amino acids—syntheses, occurrence in natural products, and components of β‐peptides^1,2

Benzyl N‐[(Benzyloxy)methyl]carbamate: An Improved Aminomethylation Electrophile for the Synthesis of (Benzyloxy)carbonyl (Cbz)‐Protected Chiral β²‐Amino Acids