Preparation of 4-alkoxy Substituted Pyrrolopyrimidines for CSF-1R Structure-Activity Relationship Studies
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- Institutt for kjemi 
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Overexpression of the colony stimulating factor 1 (CSF-1R), a tyrosine kinase, is linked to numerous diseases, which can be treated by small molecule inhibitors. Over the course of this master thesis, four new alkoxylated pyrrolopyrimdines, with an ether group at C-4, were synthesized. The final compounds were tested for their activity towards the inhibition of (CSF-1R) and epidermal growth factor receptor (EGFR). First, the pyrrole group of the commercially available 4-chloro-7Hpyrrolo[2,3-d]pyrimidine (3) was protected using 2-(trimethylsilyl)-ethoxymethyl (SEM-Cl, 4) in 24-81% yield. Through directed lithiation C-6 was iodinated to give 4-chloro-6-iodo 7-((2-(trimethylsilyl)ethoxy)methyl)-7H-pyrrolo[2,3d]pyrimidine (7, Scheme 1) in 92-93% yield. Alkoxylations at C-4 were performed on compounds 7 and 13 (13-85%, Scheme 2). Reaction times were reduced by using higher temperatures, but higher temperatures caused decomposition. Alkoxylation using phenol (9) was also investigated in a small study via microwave reactor, but when the same conditions were applied for the reaction with (rac)-2,2,2-trifluoro-1-phenylethan-1-ol ((rac)-19), no product was obtained because of decomposition. Overall, alkoxylations using the trifluorophenylethanols lead to lower yields also due to decomposition. Following the alkoxylation (Route A) Suzuki couplings, to introduce a sp2-sp2 bond at C-6 (yields: 65-73%), and deprotection were used to reach the final compounds (yields: 65-83%). Further work showed that the alkoxylation and Suzuki reactions can be interchanged (Route B). In this pathway, the Suzuki reaction gave 80-81% yield but the alkoxylation reactions initially performed worse achieving 13-70% yield. Overall, yield improvement required a lot of individual fine tuning. In the Suzuki reaction, temperatures of 60 °C gave higher yields, than reactions performed at 100 °C. Both catalyst systems, PdCl2dppf and XPhos 2nd generation, have been applied successfully. The two step deprotection in DCM/TFA and THF/NaHCO3 gave yields between 65-83%. Loss in yields were mostly due to issues during the purification process. For the final compound 23 IC50 values of 1.48 nM for the inhibition of CSF-1R were measured and the inhibition concentration profile is superior to the internal standard PLX3397 (IC50 = 10.57 nM). EGFR is also inhibited by 94% at the maximum test concentration of 500 nM. The enantioenriched compounds (R)-24, (S)-24 showed a low inhibitory effect on both and expressed IC50 values >1000 nM.