NMR of Terminal Oxygen. Part 14. Kinetically stabilized simple enols containing methylated uracil groups: Application of a17O-NMR test of H-bonding

Autor:	Jin Cong Zhuo, Hans Dahn, Hugo Wyler, Peter Péchy
Rok vydání:	1994
Předmět:	Oxygen-17 Steric effects Hydrogen bond Stereochemistry Organic Chemistry Uracil Biochemistry Medicinal chemistry Enol Catalysis Inorganic Chemistry NMR spectra database chemistry.chemical_compound chemistry Amide Drug Discovery Physical and Theoretical Chemistry Solvent effects
Zdroj:	Helvetica Chimica Acta. 77:317-322
ISSN:	0018-019X
Popis:	In the crystalline N,N′-dimethylated uracil derivatives 2a, b, the kinetically stabilized enol group forms an H-bond with OC(4), as demonstrated by increased shielding of specifically labelled 2a and 2b in the 17O-NMR spectra (Δδ(17O)(C(4)—O) −30 ppm); absence of dilution and solvent effects show that the H-bridge is intra-molecular, forming an eight-membered chelate ring. The (apparent) shielding effect Δδ(17O) in 2a, b is larger than that in salicylamide. The strong H-bond explains why the enols 2, in spite of the absence of steric hindrance, are kinetically stabilized.
Databáze:	OpenAIRE
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