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Molecular orbital studies on nucleoside antibiotics V. Conformation of pyrazofurins
Author(s) -
Chatterjee C. L.,
Saran Anil
Publication year - 1981
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560200711
Subject(s) - anomer , chemistry , intramolecular force , hydrogen bond , aqueous solution , stereochemistry , anomeric effect , nucleoside , computational chemistry , crystallography , molecule , organic chemistry
Conformational properties of pyrazofurins, which were previously designated as pyrazomycins in both β‐ and α‐anomeric forms, have been investigated by the PCILO method. The results indicate that the most preferred conformation for β anomer is anti‐gg , while that for α anomer is syn‐gg when intramolecular hydrogen bonding between sugar and the base is allowed. However, in the absence such hydrogen bonding, which mimicks the situation in aqueous solution, both β and α pyrazofurins show exactly similar preference for anti‐gg conformation. The biological significance of this result has been discussed. Further the β anomer is energetically more favorable than the α anomer. This result is in agreement with the experimental observations, which indicate that β pyrazofurin is more populated than a pyrazofurin in aqueous solution at room temperature.