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Conformational properties of diastereomeric 5′‐O‐DMT‐2′deoxythymidine 3′‐O‐(S‐methyl‐methanephosphonothiolate)s and ‐(se‐methyl‐methanephosphonoselenolate)s in solution as studied by NMR methods
Author(s) -
GácsBaitz Eszter,
Wozniak Lucyna A.,
KajtárPeredy Mária
Publication year - 2000
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/1520-636x(2000)12:9<675::aid-chir6>3.0.co;2-l
Subject(s) - chemistry , diastereomer , stereochemistry , computational chemistry
Stereochemical characterization of diastereomerically pure 5′‐O‐DMT‐2′deoxythymidine 3′‐O‐(S‐methyl‐methanephosphonothiolate)s and ‐(Se‐methyl‐methane‐phosphono‐selenolate)s by NMR methods are reported. 1 H‐ 1 H, 1 H‐ 31 P, and 13 C‐ 31 P coupling constants and nuclear overhauser enhancement (NOE) connectivities from transverse cross‐relaxation experiments in rotating frame (T‐ROESY) were measured to correlate the conformational properties of the isomers with the absolute configurations at the phosphorus obtained from X‐ray studies of the relatives of S p configured isomers. Conformational differences between the stereoisomers were found to be restricted to the different orientation of the C3′−O3′‐P bond. The NMR data reflected the preferred ϵ − conformation for the S p isomers, while in the R p isomers the conformational equilibrium was shifted toward the ϵ t domain. These results also indicated that for 5′‐protected mononucleotides the absolute configuration at the phosphorus atom can be inferred from the NOE experiments and the trends observed in vicinal carbon‐phosphorus coupling constants. Chirality 12:675–680, 2000. © 2000 Wiley‐Liss, Inc.