Here is a very neat result from Jon Ellman’s lab at Yale. As part of a study documented in Org. Lett. (http://pubs.acs.org/doi/abs/10.1021/ol100470g), an interesting observation was made: the intended nitrogen-driven Mitsunobu process did not take place. Instead, a cyclopropane has been formed:

Building on this observation, Andrade’s lab showed a really cool cascade process that ultimately enabled a short synthesis of (-) melotenine A (http://onlinelibrary.wiley.com/doi/10.1002/anie.201302517/abstract). I think the mechanism is really interesting. Cascade reactions rule!