Helix-Forming Propensity of Aliphatic Urea Oligomers Incorporating Noncanonical Residue Substitution Patterns was written by Pendem, Nagendar;Douat, Celine;Claudon, Paul;Laguerre, Michel;Castano, Sabine;Desbat, Bernard;Cavagnat, Dominique;Ennifar, Eric;Kauffmann, Brice;Guichard, Gilles. And the article was included in Journal of the American Chemical Society in 2013.Safety of tert-Butyl ((1R,2R)-2-hydroxycyclohexyl)carbamate This article mentions the following:
Aliphatic N,N’-linked oligoureas are peptidomimetic foldamers that adopt a well-defined helical secondary structure stabilized by a collection of remote three-center H-bonds closing 12- and 14-membered pseudorings. Delineating the rules that govern helix formation depending on the nature of constituent units is of practical utility if one aims to utilize this helical fold to place side chains in a given arrangement and elaborate functional helixes. In this work, we tested whether the helix geometry is compatible with alternative substitution patterns. The central -NH-CH(R)-CH2-NH-CO- residue in a model oligourea pentamer sequence was replaced by guest units bearing various substitution patterns [e.g., -NH-CH2-CH2-NH-CO-, -NH-CH2-CH(R)-NH-CO-, and -NH-CH(R1)-CH(R2)-NH-CO-], levels of preorganization (cyclic vs acyclic residues), and stereochemistries, and the helix formation was systematically assessed. The extent of helix perturbation or stabilization was primarily monitored in solution by Fourier transform IR, NMR, and electronic CD spectroscopies. Our results indicate that although three new substitution patterns were accommodated in the 2.5-helix, the helical urea backbone in short oligomers is particularly sensitive to variations in the residue substitution pattern (position and stereochem.). For example, the trans-1,2-diaminocyclohexane unit was exptl. found to break the helix nucleation, but the corresponding cis unit did not. Theor. calculations helped to rationalize these results. The conformational preferences in this series of oligoureas were also studied at high resolution by X-ray structure analyses of a representative set of modified oligomers. In the experiment, the researchers used many compounds, for example, tert-Butyl ((1R,2R)-2-hydroxycyclohexyl)carbamate (cas: 155975-19-2Safety of tert-Butyl ((1R,2R)-2-hydroxycyclohexyl)carbamate).
tert-Butyl ((1R,2R)-2-hydroxycyclohexyl)carbamate (cas: 155975-19-2) belongs to alcohols. Alkyl halides are often synthesized from alcohols, in effect substituting a halogen atom for the hydroxyl group. Secondary alcohols are easily oxidized without breaking carbon-carbon bonds only as far as the ketone stage. No further oxidation is seen except under very stringent conditions.Safety of tert-Butyl ((1R,2R)-2-hydroxycyclohexyl)carbamate
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