The lipid binding ability of four urea-picket porphyrins designed to bind to both the phosphate anion portion as well as the glycerol hydroxyl groups of phosphatidylglycerol (PG) has been investigated. Isothermal titration calorimetry (ITC) and (1)H NMR were used to determine the receptor's stoichiometry of binding, association constants, and both the enthalpy and entropy of binding with the PG anion. Spectral evidence shows that the phosphate anion portion of PG is hydrogen bonded to the urea groups of the receptors. This binding interaction orients the PG anion in the receptor pocket such that its glycerol hydroxyl groups can align with a third urea picket, and results are furnished that suggest this multifunctional interaction does occur. The structure of the entire picket was found to influence the enthalpy and entropy of lipid binding. The synthesis of tetrabutlyammonium phosphatidylglycerol (TBAPG), and a detailed spectral characterization of its headgroup, is also presented.
A method for the one-step C-ureidoalkylation of phenol, anisole, or aniline rings furnishing ArCH(2)NHCONHR (Ar = benzyl) products in moderate to good yields is described. With phenol ring systems, higher yields were attained when the reaction was worked up with an acidic ethanethiol addition to cleave any O-ureidoalkylation products that formed during the reaction.
Urea derivatives P 0490A Convenient, One-Step Synthesis of Benzyl (Ar) Ureas of the Type ArCH 2 NHCONHR from Ar and R 1 OCH 2 NHCONHR via Ureidoalkylation. -Anisoles, anilines, and phenols smoothly react with urea derivatives of type (II) and (V) to afford benzyl ureas in acceptable yields. Mono-and bis-ureidoalkylation is possible. -(MEECE, F. A.; JAYASINGHE, C.; HISTAND, G.; BURNS*, D. H.; J. Org.
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