PTC can provide a safe, highly effective approach to reactons with NaCN and NaN3. First of all, reaction conditions are usually basic, which safely keeps NaCN and NaN3 in solution as the anions. Second, because the nucleophiles are less solvated under PTC conditions than in DMSO or similar solvents, PTC provides more reactive conditions. Hence fewer equivalents of NaCN and NaN3 are needed, and reactions are generally faster.Of course, there may be emulsion difficulties on the other side -- but those can be dealt with, too. Phase-transfer catalysis is your friend -- so don't be afraid to reach for the tetrabutylammonium bromide.
Wednesday, December 22, 2010
Process Wednesday: phase-transfer catalyst
I have seen it with my own eyes: the power of phase-transfer catalysis is remarkable. But you guys shouldn't trust me -- as always, you should trust Neal Anderson: