1. In situ Click chemistry
Mgr. Juraj Dobiaš
KOCH, PRIF UK

2. What is Click Chemistry ?
joining molecules by an „ideal chemical reaction“
fast, irreversible reaction, simple conditions
starting materials are readily available, stable (biocompatible)
high yielding, high atom economy, wide application
large thermodynamic driving force to give predictable outcome
easy work-up and product isolation
preferably proceeding in water, insensitive to oxygen
the best by some fusion reaction:

3. Synthesis of 1,2,3-triazoles
Thermal Huisgen [3+2] cycloaddition
80-120°C, 12-24h, both regioisomers ca 1/1 E#A= kcal/mol
Cu(I) catalyzed (CuSO4 / sodium L-ascorbate)
only 1,4-regioisomer, high yield, rt, t-BuOH / water environment E#A= 15 kcal/mol (106 times faster than Huisgen r.)
Ru catalyzed (Cp*RuCl(PPh3)2)
mainly 1,5-regioisomer
Huisgen
2002, Fokin, Sharpless Melda
2005, Fokin Shrapless

4. Click Chemistry Exploitation
Material sciences (copolymers, functionalized surfaces, adhesives, dendrimers, large macrocycles, ....)
Bioorganic chemistry (biosensors, bioconjugates: tagging of proteins, nucleotides or in situ whole organisms, SPAAC – no metal)
Drug development – Medicinal Chemistry

5. MMps inhibitors 8 Cu(I) 12 MMP7 selective, low mcM inhibitors
Org. Lett

6. In Situ Click Chemistry (TDS) target driven synthesis
TDS reduces the number of inactive compounds
Compensate the lack of precision in the predictive ability of in Silico chemistry
In situ AA Click chemistry is completely biocompatible, uses irreversible reaction to unite reagents inside the protein´s binding pocket
Target will pick best fitting ligands from diverse sets of chemical building blocks
Significant portion of the activation barrier is entropic (pieces have to approach each other in precisely the right orientation), pre-assembly of building blocks on the target active site can accelerate cycloaddition.
DDT

7. Observation of the controlled assembly of preclick components in the in situ click chemistry generation of a chitinase inhibitor
chitinase inhibitors fight against infectious and inflammatory diseases – onchocerciasis.
screening of over 10,000 extracts from soil microorganisms
2013 PNAS

8. In situ click

9. Triazole komplex
3WD1

10. Captured transition state
Alkene doesn’t cocrystalyze without azide even at high concentration – induced fit.
Different pose of azide with and without alkene – double induced fit.
3WD2
3WD4

11. Summary
Identified triazole inhibitor of chinase B by in situ click chemistry approach.
Solved crystal structure of transition state with alkene analog.
Performed DFT calculations, but did not observe any enthaplic barrier decrease.
Confirmed in situ click chemistry principle that increase in reaction rate is caused by entropic factors and greater effective concentration.
Solved crystal structures that demonstrate protein flexibility and lack of in silico methods accuracy.