The Synaptic Leap

I've been working for six weeks now with the Todd Research Group at Sydney University as part of an undergraduate summer research program. The aim of my project is to synthesise analogues of this group of hits from the  antimalarial dataset released by GSK. They are referred to here as 'near neighbours' because they share the arylpyrrole moiety present in the two hits (TCMDC 123812 and 123794) Paul has been working on, but have a thiazolodinone side chain. The major components of my project are:

We have received encouraging biological results for the analogues we sent for testing before Christmas. Mat has discussed this here on TSL and on G+. Our best hit came from the "near-neighbour" compound and the original GSK hits came out slightly less active than in their original high throughput screen. However, Paul Willis at MMV rates TCMDC-123794 as a better lead than PMY 14-1 (TSL post).

 I have just packaged up TCMDC-123794 (PMY 11-2) and -123812 (PMY 10-2) along with the parent acid (PMY 8-2), ester (PMY 6-1), aldehyde (PMY 2-4), near neighbour analogue (PMY 14-1) and also the acylurea by-product (PMY 12-1-A). These have been sent to GSK Tres Cantos where the original study was carried out for further testing.

I'm now happy with the data for TCMDC-123812 and TCMDC-123794. A bit of usual practical annoynce with TCMDC-123794 caused some trivial issues, namely a bit of repurification and acetone in the final spectra. These have now been taken care of and the compounds are ready for testing!
I've summarised the various intermediates and other compounds that are in the works on OpenWetWare. Please get in touch if you're interested in testing them.

Last week I was talking with Lei Liu from Tsinghua University, who was visiting Sydney to give a talk on his synthetic methodology research. I showed him the compounds that are the starting point of the open source drug discovery project for malaria, the arylpyrrole set. He said he'd seen these compounds before, in a different context, and after a little searching around we found the relevant paper here.

I'm now fairly confident that I've made TCMDC-123794 and TCMDC-123812. By fairly confident I mean that I've got a reasonable looking but crude 1H NMR and low res. mass spec of both of the compounds. They are not clean by NMR after a column and the yield of the reaction was pretty bad (~20%). Still this isn't too bad for a first go, using a quick and dirty acid chloride. Most of the mass seems to go toward turning the acid into the anhydride. This is supported by NMR but mass spec hasn't given a positive result so far.

Ok now I'm getting close to TCMDC-123812/123794. A slight change of tack for the alternative core synthesis seems to have paid off. First alkylation of ethyl acetoacetate with chloroacetone and then condensation with 4-fluoroaniline appears to have given the pyrrole with an ester on the 3-position quite nicely in 61% yield over the two steps after recrystallisation (PMY 8-1). Sometimes it just pays to change the plan completely when you feel like progress is slow.

In the last couple of weeks my time has mostly been spent trying to figure out whats going on in the oxidation of pyrrole-3-carbaldehyde to the corresponding acid.