Monosubstituted tricyclo [2.1. 0.02, 5] pentan-3-one derivatives have been synthesised and subjected to hydride reduction. Quite unexpectedly and in contrast to earlier observations in related systems, anti-selectivity has been encountered in these substrates. Computational studies employing various models reproduce the observed facial preference and indicate that the causative factor for the anti-preference could be the polarization of the C1 C5 ...