[reaction: see text] A general and efficient copper-catalyzed method for the amidation of vinyl bromides and iodides has been developed. This protocol uses a combination of 5 mol % copper iodide and 20 mol % N,N'-dimethyl ethylenediamine. Substrates bearing ester, silyl ether, and amino groups were successfully coupled under the reaction conditions. The double bond geometry of the vinyl halides was retained under the reaction conditions.

[reaction: see text] A simple and mild method for the coupling of aryl iodides and aliphatic alcohols that does not require the use of alkoxide bases is described. The reactions can be performed in neat alcohol. For more precious alcohols, the etherification was carried out in toluene as solvent using 2 equiv of alcohol. Additionally, the cross-coupling of an optically active benzylic alcohol with an unactivated aryl halide was demonstrated to proceed with complete retention of configuration.

[reaction: see text] Methods for synthesizing N-aryl beta-amino alcohols and O-aryl beta-amino alcohols are described. The presence of a neighboring hydroxyl or amino group, respectively, is thought to activate beta-amino alcohols toward these transformations. These protocols significantly increase access to a variety of arylated beta-amino alcohols.

Length-dependent helical propensities w Ala (n,T) at T = 10, 25, and 60 °C are assigned from t/c values and NMR 13 C chemical shifts for series 1 peptides TrpLys m Inp 2 t Leu-Ala n t LeuInp 2 Lys m NH 2 , n = 15, 19, and 25, m = 5, in water. Van't Hoff analysis of w Ala (n,T) show that α-helix formation is primarily enthalpy-driven. For series 2 peptides Ac-Trp Lys 5 Inp 2 t Leu-β AspHel-Ala nbeta-t LeuInp 2 Lys 5 NH 2 , n = 12 and 22, which contain exceptionally helical Ala n cores, protection factor-derived fractional helicities FH are assigned in the range 10-30 °C in water and used to calibrate temperature-dependent CD ellipticities [θ] λ,H,n,T . These are applied to CD data for series 1 peptides, 12 ≤ n ≤ 45, to confirm the w Ala (n,T) assignments at T = 25 and 60 °C. The [θ] λ,H,n,T are temperature dependent within the wavelength region, 222 ± 12 nm, and yield a temperature correction for calculation of FH from experimental values of [θ] 222,n,T,Exp .

NMR and CD studies are reported for two length series of solubilized, spaced, highly helical polyalanines that are N-capped by the optimal helix stabilizer β Asp-Hel and C-capped by β-aminoalanine beta and that are studied in water at 2 °C, pH 1-8. NMR analysis yields a structural characterization of the peptide Ac β AspHelAla 8 betaNH 2 and selected members of one β AspHelAla n beta series. At pH > 4.5 the β AspHel cap provides a preorganized triad of carboxylate anion and two amide residues that is complementary to the helical polyalanine Nterminus. The C-terminal β-aminoalanine assumes a helix-stabilizing conformation consistent with literature precedents. H(N)CO NMR experiments applied to capped, uniformly 13 C-and 15 N-labeled Ala 8 and Ala 12 peptides define Ala n hydrogen bonding signatures as α-helical without detectable 3 10 character. Relative NH→ND exchange rates yield site protection factors PF i that define uniquely high fractional helicities FH for the peptide Ala n regions. These Ala n calibration series, studied in water and lacking helix-stabilizing tertiary structure, yield the first 13 C NMR chemical shifts, 3 J HNHα coupling constants, and CD ellipticities [θ Molar ] λ,n characteristic of a fully helical alanine within an Ala n context. CD data are used to assign parameters X and [θ] λ,∞ , required for rigorous calculation of FH values from CD ellipticities.