Site-selective organic transformations are commonly required in the synthesis of complex molecules. By employing a bespoke metal-organic framework (MOF, 1·[Mn(CO)N]), in which coordinated azide anions are precisely positioned within 1D channels, we present a strategy for the site-selective transformation of dialkynes into alkyne-functionalized triazoles. As an illustration of this approach, 1,7-octadiyne-3,6-dione stoichiometrically furnishes the mono-"click" product N-methyl-4-hex-5'-ynl-1',4'-dione-1,2,3-triazole with only trace bis-triazole side-product. Stepwise insights into conversions of the MOF reaction vessel were obtained by X-ray crystallography, demonstrating that the reactive sites are "isolated" from one another. Single-crystal to single-crystal transformations of the Mn(I)-metalated material 1·[Mn(CO)(HO)]Br to the corresponding azide species 1·[Mn(CO)N] with sodium azide, followed by a series of [3+2] azide-alkyne cycloaddition reactions, are reported. The final liberation of the "click" products from the porous material is achieved by N-alkylation with MeBr, which regenerates starting MOF 1·[Mn(CO)(HO)]Br and releases the organic products, as characterized by NMR spectroscopy and mass spectrometry. Once the dialkyne length exceeds the azide separation, site selectivity is lost, confirming the critical importance of isolated azide moieties for this strategy. We postulate that carefully designed MOFs can act as physical protecting groups to facilitate other site-selective and chemoselective transformations.
Densities and speeds of sound for the pure as well as binary mixtures of 1,2-butanediol and benzyl alcohol, 2-phenylethanol, 2-butanol, and 1,3-butanediol were measured over the 0 to 1 composition range and at six different temperatures between 298.150 K and 323.150 K with an interval of 5 K and at atmospheric pressure using a vibrating tube densimeter.The experimental values were used to calculate excess molar volume, V m E , excess isentropic compressibility, K S E , excess thermal expansion coefficient, α p E , infinite partial molar volumes, V̅ i ∞ and excess partial molar volumes at infinite dilution, V̅ i E,∞ . The sign and magnitude of mixing quantities have been used to discuss the nature and strength of molecular interactions in binary mixtures. The calculated excess values and deviation quantities were fitted to the Redlich−Kister polynomials equation. Furthermore, it has been checked how the calculated values of densities and excess molar volumes using the Tao−Mason equation of state compare with the experimental ones.
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