The crystal structure of clopidol (3,5-dichloro-2,6-dimethyl-4-pyridinol)

Intermolecular N–H...O hydrogen bonds assisted by resonance. Heteroconjugated systems as hydrogen-bond-strengthening functional groups

“…Hydrogen-bond topology: hydrogen-bond connectivities represented by means of: (a) our notation described in the text; (b) EMIl notation (Etter et ai., 1990); (c) EMB notation but taking into account RAHB (Gilli et al, 1989). Mastropaolo, Camerman & Camerman (1991); (k) Ohms, Guth, Hellner, DannOhl & Schweig (1984); (/) Schmalle, H~ggi & Dubler (1988); (m) Prout et al (1994); (n) Ferretti, Bertolasi, Gilli & Borea (1985); (o) Boer (1972); (t7) Bradshaw, Guynn, Wood, Wilson, Dalley & Izatt (1987); (q) Lowe, Schwalbe & Williams (1987); (r) Low, Tollin, Brand & Wilson (1986); (s) Watt, Martin, Duchamp, Mizsak, Nielson & Prairie (1988); (t) Smith, Bobe, Minnetian, Hope & Yanuck (1985). In the remaining examples (7 and 35-39), N.--O distances are rather short (2.734-2.856,~,), although the C:O and NH moieties apparently belong to a O---C--C--NmH non-conjugated moiety.…”

Crystal structure of 2,6-dimethyl-4-pyridone hemihydrate

“…hydrogen bonds, which are also observed in the close derivative Clopidol (Boer, 1972). While the title compound crystallizes in a 2:1 ratio of pyridone to water, the hydrate of the parent molecule crystallizes in a 5:6 ratio (Jones, 2001).…”

“…For the title compound bound to zirconium, see: Castillo et al (1987). For the structure of a chloro-substituted variant of the title compound, see : Boer (1972 Hydrogen-bond geometry (Å , ). 18166 3Symmetry code: (i) x À 1 2 ; Ày þ 1 2 ; z.…”

A Comparison of the Enamino Carbonyl Conjugation Efficiency for Hydrogen Bonding Formation in Pyridone and Dihydropyridone Systems

“…In ETPY there are three alternatives, (1) 0 ( 13)=C (4) [9,20,21]. This expectation is supported by the com parison o f H OM A indexes [22] of all conju gation pathw ays (Table IV) [24] together with the numbering scheme.…”