353514-75-7

Upstream product

• 129-64-6 3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride 
• 4070-48-8 L-Valine methyl ester 
• 6306-52-1 L-valine methylester hydrochloride 
• 824393-57-9 (Z)-3-((S)-1-Methoxycarbonyl-2-methyl-propylcarbamoyl)-acrylic acid 
• 824393-54-6 methyl N,N-maleoyl-L-valinate 
• 542-92-7 cyclopenta-1,3-diene 
• 2746-19-2 (1R,2R,6S,7S)-4-oxa-tricyclo[5.2.1.0^2,6]dec-8-ene-3,5-dione 

Relevant academic research and scientific papers

Synthesis and properties of chiral N,N-maleoyl derivatives and Diels-Alder reactions with cyclopentadiene

Maleyl amino acid derivatives were prepared from maleic anhydride and cyclized by reaction with ZnCl2 and hexamethyldisilazane yielding maleoyl derivatives. These derivatives were used as dienophiles in cycloadditions with cyclopentadiene. The

Demonstration of endo-cis-(2S,3R)-Bicyclo[2.2.1]hept-5-en-2,3 dicarbonyl unit as a reverse-turn scaffold and nucleator of two-stranded parallel β- sheets: Design, synthesis, crystal structure, and self-assembling properties of norborneno peptide analogues

endo-cis-(2S,3R)-Bicyclo[2.2.1]hept-5-en (norbornene) dicarbonyl unit with a built-in U-architecture has been demonstrated to be an excellent reverse-turn molecular scaffold. A large variety of endo-cis-(2S,3R)- norborneno bispeptides containing almost all of the coded amino acids were synthesized and examined for conformational preferences by 1H NMR, FT-IR, CD, and X-ray crystallographic studies. While FT-IR and 1H NMR variable- temperature studies ruled out the presence of any significant amount of intramolecular hydrogen bonding in simple bispeptides (3a-h) (except in Aib bispeptide), the CD studies were clearly in favor of a β-tum type structure. Single-crystal X-ray studies on Aib, Val and Leu containing norborneno bispeptides (3b-d) provided convincing proof for the presence of reverse- turn conformation. While the interstrand C(α)-C(α') distances (5.2-5.7 A?) were well within the range of those for β-turn structures, no interstrand intramolecular hydrogen bonding was seen in Val and Leu bispeptides; the Aib bispeptide forms a seven-membered hydrogen-bonded ring, thus, showing that the norbornene (2S, 3R)-dicarbonyl template assembles peptide chains in reverse-turn conformation by virtue of its built-in U-shaped architecture at these positions, and hydrogen bonding may not be necessary to stabilize the turn structure. The endo-cis-(2S,3R) orientation of bispeptide chains is essential for turn structure as shown by the crystal structure of trans- (2R,3R) and trans-(2S,3S) derivative of Val bispeptide wherein the two peptide chains move away from each other with the C(α)-C(α') distance increasing to 7.1-8.2 A?. The norbornene 5,6-double bond was hydrogenated to 5,6-dihydro derivative which showed almost the same CD spectrum as its olefinic analogue. Oxidative cleavage [Ru (VIII)] of the 5,6-double bond in norborneno bispeptides, as demonstrated with Leu bispeptide, afforded novel cyclopentanoid peptide analogues. The promise of norbornene unit as a template for nucleating the formation of two-stranded parallel β-sheets with minimum structural complexity is shown by the preparation of higher members of norbomeno bispeptides with the general structure NBE(Pep)2 [NBE = endo- cis-(2S,3R)-bicyclo[2.2.1]hept-5-en (norbornene) dicarbonyl unit; Pep = peptide strand with two, three, or four (same or different) amino acid residues]. In 1H NMR, the high 3J(HNα) values (7.0-9.3 Hz) observed for the amide protons (Table 3) coupled with the presence of medium to strong intrastrand sequential ROE connectivities d(αN(i,i+1)) spanning the entire three- or four-residue sequence in the peptide strands of 9a-e and 10 and the exhibition of relatively low-temperature coefficients (dδ/dT = - 0.2 to - 3.4 ppb/K) for amide protons in DMSO-d6 solvent (Table 4) clearly suggested that hydrogen-bonded β-sheet conformers dominate the population. FT-IR and CD studies provided further support for parallel β-sheet structures. A particularly unique feature of the norborneno bispeptides is their strong tendency to self-assemble in the solid state. Thus, while endocis-(2S,3R)- Aib bispeptide (3b) forms 16-membered hydrogen bonded centrosymmetric dimers, the half-ester half-acid and the dicarboxylic acid derivatives of 3b self- assemble to form highly ordered hydrogen-bonded molecular ribbons. The Val and Leu cis-(2S,3R)-bispeptides organize into hydrogen-bonded chains and the trans isomer of Val bispeptide self-assembles into hydrogen-bonded β-sheet ribbon.

The synthesis of N-norbornenyl-amino acids and esters: Monomers for the preparation of well defined polymers

Two routes to the synthesis of various norbornene containing amino acid derivatives are described. The methodology also allows the preparation of the 7-oxonorbornene analogues, and a kinetics study of the racemisation of one of the monomers is reported.