52815-81-3Relevant academic research and scientific papers
Proline-based dipeptides with two amide units as organocatalyst for the asymmetric aldol reaction of cyclohexanone with aldehydes
Chen, Fubin,Huang, Shi,Zhang, Hui,Liu, Fengying,Peng, Yungui
, p. 9585 - 9591 (2008/12/22)
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.
A convenient synthesis of amino acid p-nitroanilides; synthons in the synthesis of protease substrates
Rijkers, Dirk T. S.,Adams, Hans P. H. M.,Hemker, H. Coenraad,Tesser, Godefridus I.
, p. 11235 - 11250 (2007/10/02)
A method is described for the synthesis of N(α)-protected bi- and trifunctional amino acid p-nitroanilides. The reaction uses phosphorus oxychloride as the condensing agent. The synthesis is simple, rapid, free of racemization and affords yields between 70-90%. The synthesis can be performed not only with amino acid derivatives of the urethane type including acid-labile (Z, Boc) and base-labile (Fmoc, Msc) N(α)-protective functions or allyl-derived protections, but also with N(α)-trityl amino acids, albeit in lower yield. The reaction runs in pyridine and its mechanism implies carboxyl activation by formation of a mixed anhydride with phosphorodichloridic acid (HOPOCl2).
