No abstract

The synthesis of biomimetic helical secondary structures is sought after for the construction of innovative nanomaterials and applications in medicinal chemistry such as the development of protein-protein interactions modulators. Peptoids, a sequence-defined family of oligomers, enable a peptidomimetic strategy, especially considering the easily accessible monomer diversity and peptoid helical folding propensity. However, cis-trans isomerization of the backbone tertiary amides may impair the peptoid's adoption of stable secondary structures, notably the all-cis polyproline I-like helical conformation. Here we show that cis-inducing NtBu achiral monomers strategically positioned within chiral sequences may reinforce the degree of peptoid helicity, although a reduced content of chiral side chains. The design principles presented here will undoubtedly help to achieve more conformationally stable helical peptoids with desired functions.

et al.. Synthesis and mesomorphic properties of liquid crystals containing a perfluorinated segment via different Abstract This study presents the synthesis and mesomorphic properties of a series of biphenyl benzoate liquid crystals carrying a perfluorinated segment, via three uncommon flexible linkers. In particular, a (E)-2-propenyloxy linker was used which was issued from an elegant regioselective dehydrohalogenation reaction. The remarkable microsegregation effect of the perfluorinated segment, led to the formation of highly stable untilted lamellar mesophases, including a specific SmE pseudo-B mesophase. For all mesophases, the molecular packing corresponds to a monolayer arrangement of the mesogenic parts and a partial intercalation of the perfluorinated chains. -heptadecafluoronon-2-enyl)oxy}-(1,1'biphenyl)-4-yl benzoate (4b). Yield: 83%: 1 H NMR( CDCl 3 ) δ 8.25 (d, 2H, J = 7.2 Hz), 7.5-7.7 (m, 7H), 7.25 (d, 2H, J = 8.7 Hz), 7.0 (d, 2H, J = 8.7 Hz), 6.66 (dtt, 1H, 3 J trans = 15.6 Hz, 4 J H-F = 2.1 Hz, CH=CH-CH 2 O, E enantiomer), 6.15 (dt, 1H, 3 J trans = 15.6 Hz, 3 J H-F = 12.6 Hz, CF 2 -CH=CH-, E enantiomer), 4.75 (m, 2H, -CH 2 O-). 13 C NMR (CDCl 3 ) δ(ppm) 165.2 (C=O), 157.4, 150.0, 138.4, 137.2 (t, 3

Benzonitrile-hydrogen peroxide oxidation of prochiral and chiral imines 1a-h leads to racemic (E)-oxaziridines (R,R/S,S) and nonracemic (E)-oxaziridines (R,R,R/S,S,R) 2a-h, respectively.Oxidation of imines with organic peracids is the most useful method for preparing oxaziridines (1-4). These reagents convert anti-N-arylidenealkylamines (3,5,6) to a mixture of (E) and (Z)-oxaziridines (3,7-10) according to a two-step mechanism (11-13). Note that 2-tert-alkyl-3-aryloxaziridines were obtained exclusively in the (E) form because of the bulkiness of the substituents. Until now, no stereospecific synthesis of 2-alkyl-3-aryl-oxaziridines has been reported. ORDER REPRINTS 264KRAÏEM ET AL. Scheme 1.

Potential biologically active derivatives of the 2-Amino-5-aryl or Formylpyridine-3-Carbonitriles (2a-d) were prepared by the cyclocondensation reaction of vinamidinium salts with malonitrile. The structures of these compounds were established on the basis of elemental (C, H,N) and spectral (1 H-NMR, 13 C-NMR and spectral data) analysis. The compounds were screened for their antifungal and antibacterial activity. The compound 2-amino-5-formylpyridine-3-carbonitrile was found to be the most potent compound of series.