Hydrogen bonding continued steroids

Indications that the simple steric polarization model for the y-gauche interaction (39, 40) may be insufficient now come from a variety of sources. There are a number of examples in the literature where the three bond interaction involves a heteroatom which may have unshared pairs of electrons but no bond to hydrogen by which the steric polarization model could be evoked. An illustration of this may be seen from some steroid 13C data recently acquired in our laboratory. These are shown in Table I where the numbering system initiated in the Blunt and Stothers review (1) is continued. 

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