73397-27-0Relevant academic research and scientific papers
TAXANE DERIVATIVES AND PROCESSES FOR THE PREPARATION THEREOF
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Page 4; 14-16, (2008/06/13)
The invention discloses an oxazolidine intermediate for the synthesis of 14- beta -hydroxy-1,14-carbonate-baccatines bearing a 13-isoserine substituent, and a process for the preparation thereof.
Synthesis and CD spectra of fluoro- and hydroxy-substituted β-peptides
Gessier, Francois,Noti, Christian,Rueping, Magnus,Seebach, Dieter
, p. 1862 - 1870 (2007/10/03)
β-Amino acids 1-3 with OH and F substituents in the α-position have been prepared (Scheme) from the natural (S)-α-amino acids alanine, valine, and leucine, and incorporated into β-hexa- and β-heptapeptides 4-12. The peptide syntheses were performed according to a conventional solution strategy (Boc/Bn protection) with fragment coupling. The new β-peptides with (series a) and without (series b) terminal protection were isolated in HPLC-pure form and characterized by NMR spectroscopy and MALDI mass spectrometry. The chemical properties as well as the patterns of the CD spectra (Figs. 3-5) depend upon constitution (OH, F, F2 substitution) and configuration (l or u) of the amino acid residues, upon the total number of OH and F substituents in the peptide chain, and upon the solvent used (H2O, MeOH, CF3CH2OH, (CF3)2CHOH). No reliable clues regarding the structures can be obtained from these CD spectra. Only a full NMR analysis will be able to answer the questions: a) with which known secondary structures (Figs. 1 and 2) of β-peptides are the OH and F derivatives compatible? b) Are new secondary structures enforced by the polar and/or H-bonding backbone substituents? Furthermore, the β-peptides described here will enable us to study changes in chemical, enzymatic, and metabolic stability, and in physiological properties caused by the heteroatoms.
Renin Inhibitors. Substitution of the Leucyl Residues of Leu-Leu-Val-Phe-OCH3 with 3-Amino-2-hydroxy-5-methylhexanoic Acid
Johnson, Rodney L.
, p. 605 - 610 (2007/10/02)
The 2S,3S and 2R,3S diastereoisomers of the hydroxy amino acid 3-amino-2-hydroxy-5-methylhexanoic acid (AHMHA) were synthesized and substituted for the leucyl residues of Leu-Leu-Val-Phe-OCH3 to yield the following analogues: AHMHA-Leu-Val-Phe-OCH3, AHMHA
Synthesis of (2S,3R)-3-Amino-2-hydroxy-5-methylhexanoic Acid Derivatives. Application to the Synthesis of Amastatin, an Inhibitor of Aminopeptidases
Rich, Daniel H.,Moon, Byung Jo,Boparai, Amrit S.
, p. 2288 - 2290 (2007/10/02)
Methods are reported for the synthesis of optically pure derivatives of (2S,3R)-3-amino-2-hydroxy-5-methylhexanoic acid. -D-leucine methyl ester was reduced in 95percent yield with diisobutylaluminum hydride to the aldehyde which was converted via the cyanohydrin to (2RS,3R)-3-amino-2-hydroxy-5-methylhexanoic acid (AHMHA).The mixture of diastereomers was converted to the corresponding Boc-AHMHA methyl ester derivatives and separated by chromatography over silica gel.The optical purity of the diastereomers at C-3 was established by converting each to diastereomeric Boc-AHMHA-Leu-OMe and separating these dipeptides by chromatography.Pure (2S,3R)-Boc-AHMHA was coupled with valyl-valyl-aspartic acid dibenzyl ester by using dicyclohexylcarbodiimide/ 1-hydroxybenzotriazole in 63percent yield.The Boc group was removed by using trifluoroacetid acid, and the benzyl groups were removed by hydrogenolysis.The product, (2S,3R)-AHMHA-L-Val-L-Val-L-Asp, amastatin, was found to be identical with the natural product.
