The crystal structure of 1-(2,6-dichlorobenzyl)-6-hydroxy-1,4,5,6-tetrahydronicotinamide dihydrate

Optical induction in chiral crystals. I. The crystal and molecular structures of 4,4'-dimethylchalcone

“…Similar values have been observed in other methyl-substituted phenyl rings, e.g., p-methylchalcone (Rabinovich, 1974), 2,3-dimethylbenzoic acid (Smith, Florencio & GarciaBlanco, 1971), p-cresol (Bois, 1970), 1,1-di-p-tolyl- ethylene (Casalone, Gavezzotti, Mariani, Mugnoli & Simonetta, 1970) and p-toluoylacetophenone enol (Kato, 1971). The deviation from the expected value of 120 ° is consistent with observations by Carter, McPhail & Sim (1966) and Hope (1969) that aromatic substitution by electron-donating groups leads to an internal angle smaller than 120 ° on the substituted carbon, whereas electron-withdrawing groups have the opposite effect. The average length of the two single C-CHa bonds (1.Sll ,~) is in agreement with the values found in other molecules (Smith et al, 1971;Takwale & Pant, 1971;Bois, 1970;Kato, 1971).…”

Novel NADPH–cysteine covalent adduct found in the active site of an aldehyde dehydrogenase

“…The Michael addition of the cysteine thiolate to the double bond of the α,β-unsaturated nicotinamide results in a 1,2,3,4-tetrahydropyridine derivative ( Figures 1B-1D). It is, however, similar to the half-chair conformation found in other tetrahydropyridine rings resulting from alkylation at C5N or C6N [35]. These are the conformations that best fit into the F o − F c omit map of the PaBADH crystal, as shown in Figure 1(A).…”

Glyceraldehyde-3-phosphate dehydrogenase catalyzed hydration of the 5-6 double bond of reduced β-nicotinamide adenine dinucleotide (βNADH). Formation of β-6-hydroxy-1,4,5,6-tetrahydronicotinamide adenine dinucleotide

“…The X-ray crystal structure for DCB-6HTN reported by Hope (1969) provides a basis for our pmr conformational analysis of the 6HTN ring in solution. In the crystal the substituents on the C-4, C-5, and C-6 atoms are aligned in a rigid, staggered conformation.…”

“…In the crystal the substituents on the C-4, C-5, and C-6 atoms are aligned in a rigid, staggered conformation. We have calculated the dihedral angles between these substituents (Table III) using the atomic coordinates (Hope, 1969) and from these calculations have constructed the Newman projections shown in Figure 2. The important features of the conformation of the 6HTN ring in the crystal are: (1) the hydroxyl at the C-6 position is axial and (2) the protons on the C-4, C-5, and C-6 atoms are staggered with distinct axial and equatorial orientations.…”

“…The values can be varied over a range of ±0.4 Hz before significantly affecting the fit of the computergenerated spectra. a , the dihedral angle between vicinal protons calculated from the positional parameters, after translation to orthogonal coordinates, for crystalline DCB-6HTN using the data contained in Table I of Hope (1969).…”