40682-56-2Relevant academic research and scientific papers
anti-Selective Aldol Reactions of Titanium Enolates of N-Alkylideneglycinates. Stereoselective Synthesis of anti-Isomers of β-Hydroxy-α-amino Esters
Kanemasa, Shuji,Mori, Takashi,Wada, Eiji,Tatsukawa, Akira
, p. 677 - 680 (1993)
Titanium enolates of N-alkylideneglycinates and derivatives react with aldehydes to give anti-isomers of β-hydroxy-α-amino esters and derivatives.Combination of the titanium enolates, generated by transmetalation of the corresponding lithium enolates with dichlorodiisopropoxytitanium, and bulky aliphatic aldehydes is most effective for the favored formation of anti-isomers. Key Words: anti-Selective aldol reaction, Titanium enolate, N-Alkylideneglycinate, β-Hydroxy-α-amino Ester
Stereochemistry and conformation of skyllamycin, a non-ribosomally synthesized peptide from streptomyces sp. Acta 2897
Schubert, Vivien,Di Meo, Florent,Saaidi, Pierre-Loic,Bartoschek, Stefan,Fiedler, Hans-Peter,Trouillas, Patrick,Suessmuth, Roderich D.
, p. 4948 - 4955 (2014/05/06)
Skyllamycin is a non-ribosomally synthesized cyclic depsipeptide from Streptomyces sp. Acta 2897 that inhibits PDGF-signaling. The peptide scaffold contains an N-terminal cinnamoyl moiety, a β-methylation of aspartic acid, three β-hydroxylated amino acids and one rarely occurring α-hydroxy glycine. With the exception of α-hydroxy glycine, the stereochemistry of the amino acids was assigned by comparison to synthetic reference amino acids applying chiral GC-MS and Marfey-HPLC analysis. The stereochemistry of α-hydroxy glycine, which is unstable under basic and acidic conditions, was determined by conformational analysis, employing a combination of data from NOESY-NMR spectroscopy, simulated annealing and free MD simulations. The simulation procedures were applied for both R- and S-configured α-hydroxy glycine of the skyllamycin structure and compared to the NOESY data. Both methods, simulated annealing and free MD simulations independently support S-configured α-hydroxy glycine thus enabling the assignment of all stereocenters in the structure of skyllamycin and devising the role of two-component flavin dependent monooxygenase (Sky39) as S-selective.
Addition of azomethine ylides to aldehydes: Mechanistic dichotomy of differentially substituted α-imino esters
Seashore-Ludlow, Brinton,Torssell, Staffan,Somfai, Peter
scheme or table, p. 3927 - 3933 (2010/09/18)
The formal 1,3-dipolar cycloaddition of azomethine ylides and aldehydes is explored, as hydrolysis of the resulting oxazolidine product gives facile access to valuable syn-β-arylβ-hydroxy-α-amino esters. The use of using benzaldehydederived imines as the ylide precursor results in 1,3-dipolar cycloaddition with high conversions but low diastereoselec-tivity. In contrast, the employment of benzophenone-derived imines as the ylide precursor results in an aldol reaction, which gives the intermediate oxazolidine in high diastereoselectivity and requires a weak acid catalyst to achieve higher conversions.
