2/4/2013 - Prasad Reduction

This was a reaction that I had learnt in my third year organic chemistry course and has been emphasized quite a bit as a very powerful reaction to control stereoselectivity in reductions.  The Prasad Reduction, first developed in 1984, uses a boron chelating agent to tether the ketone and alcohol together, creating a favored boat transition shape, which is what drives the selection of reduction as seen below.  The reducing agent in this case is sodium borohydride, which attacks the most favorable site of reduction, which can be determined through a simple model of the boat transition state.

Image: Wikipedia