Letter to Santa Claus
Or to the Three Wise Men, depending on your preferences. Anyway, Christmas is coming, we have been good chemists this year and it is time to write our letter. Tradition says we should ask for new toys, but we are no longer kids (well, in most cases), so instead of toys we will ask for new reactions to play with. This is our wish list for the next year.
So far this year we have been very good all of the time. Here is a list of the new reactions we would like to receive from you. We know that many chemists around will send you similar lists this Christmas. Since we know you are quite busy, we are already working on some of these wishes.
- A Curtius reaction we can carry out at room temperature using a catalyst, so that temperature-sensitive substrates do not blow up. The usual Curtius conditions involve heating at 100 °C or similar.
- Nickel/palladium-catalyzed coupling of aromatic fluorides. We are tired of playing around only with iodine, bromide, and chloride. Let’s play with fluoride also.
- A benzylic oxidation that does not need KMnO4, MnO2, SeO2, or similar, because they misbehave, work up is tiresome, and purification difficult. We would like to use just a fine catalyst and air, but we could work with oxygen if needed.
- More iron-catalyzed coupling reactions. Some work has been published using iron in the usual coupling reactions, but extended, consistent, and comprehensive work would be necessary. Iron is cheaper and less toxic than palladium.
- A really effective, chemoselective reduction method of nitro groups in the presence of halides. The ideal solution would be a hydrogenation with a good catalyst, because ‘chemical’ methods involve SnCl2 (nasty), a metal in acidic media (sometimes troublesome), or similar. Although many people report that their nitro reductions work fine in the presence of halogens, usually some dehalogenation occurs.
- A good method to incorporate bulky groups by reductive amination. Sometimes, the preparation of bulky amines following the usual amination protocol is rather difficult. A good idea would be to overcome the problem using a coupling reaction with a highly reactive partner.
This is our wish list and, as you can see, it is basically a list of relatively common synthetic problems we feel remain unsolved. Most likely our readers have a wish list of their own. We would love to hear from you what synthetic problems you would like to see solved in 2009. Who knows, maybe we can be of help…