conformational equilibria of the titled compounds, 10–13, have been determined by 1HNMR and analysed in terms of steric (A(1,3) repulsion, 15) and electronic effects. The conformational equilibria of OMe and Br derivatives depend on the position and electronic properties of ω-substituent/s, attached to the doublebond, which may be rationalized in terms of “anomeric” type of resonance, 9. In contrast