111258-73-2

Upstream product

• 15761-39-4 1-(tert-butoxycarbonyl)-L-proline 
• 35373-92-3 L-phenylalanine methylamide 
• 13734-34-4 N-tert-butoxycarbonyl-L-phenylalanine 
• 109522-21-6 N-(t-butoxycarbonyl)-L-phenylalanine methylamide 

Downstream Products

• 1071841-82-1 H-L-Pro-L-Phe-NHMe 

Relevant academic research and scientific papers

Proline-based dipeptides with two amide units as organocatalyst for the asymmetric aldol reaction of cyclohexanone with aldehydes

A series of proline-based dipeptide organocatalysts with two amide units (1-16) have been developed and evaluated in the direct catalytic asymmetric aldol reactions of aldehydes with cyclohexanone. These catalysts showed good solubility in organic solvents compared with their corresponding carboxyl terminal dipeptides. The robust amide bond formation allowed structural modifications and fine tuning of catalyst properties by varying the stereo and electronic effects of the terminal amide to affect the ability of hydrogen bonding formation between the catalysts and the substrates. The reactions proceeded smoothly in high yields (up to 99%), enantioselectivities (up to 98% ee) and anti-diastereoselectivities (up to 99:1) in the presence of bifunctional organocatalyst 4 under the optimal reaction conditions.

Competitive formation of 10- and 7-membered hydrogen-bonded rings of proline-containing model peptides

Intramolecularly hydrogen-bonded structures of proline-containing model peptides with a sequence of N-tert-butoxycarbonyl-prolyl-Xaa-NHCH3 [Xaa = Gly (glycyl), Ala (alanyl), Phe (phenylalanyl), Leu (leucyl), Ile (isoleucyl), and Val (valyl)] were studied by proton nuclear magnetic resonance and infrared spectroscopy. Variation of chemical shifts of amide protons with composition change of DMSO-d6/CDCl3 mixed solvents were found to be a good measure of intramolecular hydrogen bonding of peptides in CDCl3 solution. It has been shown that 10- and 7-membered hydrogen-bonded rings, which should have the β- and γ-turn like structures in proteins, respectively, form competitively with each other. It is suggested that the equilibrium between the two hydrogen-bonded rings is determined by steric hindrance due to a side chain of the Xaa residue. Free energies for formation of the 10- and 7-membered hydrogen-bonded rings, ΔG10 and ΔG7, were estimated from the solvent composition-dependent change of the chemical shifts. A good correlation between ΔG10 and the occurrence frequencies of residues Xaa at the (i + 2)th position for the β-turns in proteins has been found.