Summer Research 2015: Second Update!

Good Evening

We are halfway down with summer research, and while the progress I’ve made is exciting, the fact that we are closer to the end of the summer is frightening as I still have much to do!

The azobenzene derivative project has been going less than stellar. I’ve having tremendous trouble separating the products via flash chromatography. I am able to get good separations for the nitrosoarene synthesis, but the azo formation reaction is causing a lot of problems. I have even tried running the solvents in 20:1 DCM:MeOH, but part of the products I need to separate come out within the first ten fractions. Recently I have gotten decent looking product separating, but there are still too many aromatic peaks, and for some unknown reason there are three alkyne peaks (despite having one alkyne residue). Thankfully, the starting unnatural amino acid I use (Boc-phe-(4′-NH2)-OH) will most likely not go into the Azo synthetase that has been developed. I deprotected the boc group with HCl today and I will try inducing an expression culture with the newly fashioned amino acid. I can check if a UAA went in by simple SDS page gel electrophoresis. To check if it is my desired UAA, I can undergo a Glaser-Hay reaction with the terminal alkyne, similar to what I did with the Protyro UAA.

The microwave clicks have been excited. I have recently been doing a cycloaddition with sepharose resin and an azide fluorophore. This has allowed me another test to find the best conditions for the copper-free reaction. I have tried using the microwave on power mode, in which it will keep a certain power level constant. After trying 100W, 200W, 300W, and 300W x 2. It seems that the 200W and 300W x 2 offer the best reaction conditions. I have confirmed this by undergoing a microwave click with hexyne and azide-TMS, which produced significantly better yields than the before small molecule microwave clicks. Hopefully this optimization will work, because I have 18 reactions to perform, extract, and column (and get good yields and NMRs!).

Thanks for reading, I will be updating in the next week or two!

-Marshall