1190398-83-4

Upstream product

• 1190398-80-1 Boc-L-Phe-D-Oxd-OH 
• 1190398-82-3 L-Phe-D-Oxd-OBn*TFA 
• 13734-34-4 N-tert-butoxycarbonyl-L-phenylalanine 
• 1089213-00-2 Boc-L-Phe-D-Oxd-OBn 

Downstream Products

• 1190398-84-5 Boc-(L-Phe-D-Oxd)2-OH 

Relevant academic research and scientific papers

Solid-state properties and vibrational circular dichroism spectroscopy in solution of hybrid foldamers stereoisomeric mixtures

Upon slow evaporation of a 1:1 diastereoisomeric mixture of Boc-(l-Phe-l-Oxd)2-OBn (1; Boc=tert-butyloxycarbonyl; l- Oxd=trans-(4S,5R)-4- carboxy 5-methyloxazolidin-2-one, Bn= benzyloxycarbonyl) and Boc-l-Phe-l-Oxd-d-Phe-l-Oxd-OBn (2) in methyl tert-butyl ether, single crystals suitable for an X-ray diffraction study were obtained. In contrast, the two pure oligomers lead to the formation of amorphous solids under any crystallization conditions. The preferential conformation of both oligomers was fully elucidated in the solid phase and compared with the known conformation of Boc-(l-Phe-d- Oxd)2-OBn (3). The preferred conformation of 1 ranges from a polyproline II (PPII) helix to b strands and we can gather that longer and more structured oligomers will form PPII helices. In contrast, compound 3 forms infinite antiparallel b-sheet structures; thus showing the strong effect of the reversal of the absolute configuration of the Oxd moieties on the secondary structure of these hybrid foldamers. The same outcome was retained in solution, as demonstrated by vibrational circular dichroism analysis. Finally, we have demonstrated that a 1:1 mixture of 1 and 2 leads to the formation of new materials with interesting properties that are missing from the two pure compounds, such as the tendency to form crystals, fibers, and globules, depending on the solvent.

Conformational studies of phe-rich foldamers by VCD spectroscopy and ab initio calculations

Employing VCD spectroscopy, we demonstrate that the structural behavior of the oligomers Boc-(l-Phe-l-Oxd)n-OBn is similar from n = 2 to n = 6; ab initio calculations for the n = 1 case provide physical insight into the conformational properties. Further information is gained by IR, 1H NMR, and ECD spectroscopies. ECD spectra suggest the presence of different conformations between n = 1 on one side and longer chain foldamers on the other side. VCD and absorption IR spectra in methanol solutions can be interpreted as indicative of a PPII structure. In the case of Boc-l-Phe-l-Oxd-OBn, VCD spectra in CCl4 and detailed DFT computational analysis allow one to demonstrate that the most populated conformers exhibit backbone dihedral angles similar to those of a PPII geometry. This is a remarkable outcome, as we had previously demonstrated that the Boc-(l-Ala-d-Oxd)n-OBn series folds in a β-band ribbon spiral that is a subtype of the 310 helix.

Nanofibers from oxazolidi-2-one containing hybrid foldamers: what is the right molecular size?

A series of oligomers of the type Boc-(L-Phe-D-Oxd)n-OBn (Boc = tert-butoxycarbonyl; Oxd = 4-methyl-5carboxy oxazolidin-2-one; Bn = benzyl) were prepared for n = 2-5. The shortest oligomer, Boc-(L-Phe-D-Oxd)2-OBn, aggregates and form