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Design and synthesis of highly reactive dienophiles for the tetrazine-trans-cyclooctene ligation.
Computation was used to design a trans-cyclooctene derivative that displays enhanced reactivity in the tetrazine-trans-cycloctene ligation, in which the eight-membered ring is forced to adopt a highly strained 'half-chair' conformation. Expand
Strain energy of small ring hydrocarbons. Influence of C-h bond dissociation energies.
Ab initio calculations at the G2, G3, and CBS-Q levels of theory have been applied to the question of the origin of ring strain in a series of unsaturated hydrocarbons, indicating a general trend that suggests that the increased ring strain (SE) of uns saturated small ring alkenes may be attributed in part to their relatively weak allylic C-H bonds. Expand
Chiral crown conformation of Rh(2)(S-PTTL)(4): enantioselective cyclopropanation with alpha-alkyl-alpha-diazoesters.
Herein, we provide crystallographic and computational evidence that Hashimoto's Rh(2)(S-PTTL)(4) catalyst adopts a "chiral crown" conformation with a reactive chiral face and an unreactive achiralExpand
Mechanism of thiolate-disulfide interchange reactions in biochemistry.
Both density functional theory (DFT) and CCSD ab initio calculations were employed in a theoretical investigation of the mechanism of thiolate-disulfide exchange reactions, finding that an S(N)2 mechanism is also implicated in both polar and nonpolar solvents. Expand
Mechanism of SN2 disulfide bond cleavage by phosphorus nucleophiles. Implications for biochemical disulfide reducing agents.
The B3LYP variant of DFT has been used to study the mechanism of S-S bond scission in dimethyl disulfide by a phosphorus nucleophile, trimethylphospine, and calculations suggest that the reaction is almost barrierless with respect to the preorganized reaction complex. Expand
Solid-state NMR and density functional theory studies of ionization states of thiamin.
The findings indicate that MAS NMR spectroscopy in conjunction with DFT calculations is a sensitive probe of ionization states in the thiamin cofactor, and calculated the magnetic shielding anisotropy tensors of C2, C6', and N4' and found excellent agreement between the computed and the experimental tensors. Expand
Spectral heterogeneity of PRODAN fluorescence in isotropic solvents revealed by multivariate photokinetic analysis.
A multivariate analysis of the fluorescence emission of 6-propionyl-2-dimethylaminonaphthalene in a series of isotropic solvents of differing polarity and hydrogen-bonding ability reveals a pair of emission components that have emission maxima that scale with the orientational polarizability. Expand
Computational studies of nucleophilic substitution at carbonyl carbon: the S(N)2 mechanism versus the tetrahedral intermediate in organic synthesis.
Results corroborate earlier suggestions that the methanolysis of acetyl chloride does not proceed through the generally assumed addition-elimination pathway with a discrete tetrahedral intermediate but is consistent with ionization of Cl(-). Expand
Electronic Requirements for Oxygen Atom Transfer from Alkyl Hydroperoxides. Model Studies on Multisubstrate Flavin-Containing Monooxygenases
Density functional calculations at the B3LYP/6-31+G(d,p) level are used to study the mechanism of 4a-hydroperoxyflavin oxidation of a series of heteroatom nucleophiles. The oxidation of xenobiotics...
Previtamin D conformations and the wavelength-dependent photoconversions of previtamin D
Abstract Conformational abundances calculated at different levels of theory have been used to derive spectral and photophysical properties of a previtamin D model compound. The individual conformerExpand