(1) This document describes research into generating molecular diversity from cyclooctatetraene (COT) and testing the inhibitory activity of generated compounds against β-glucosidase. (2) COT is reacted with electrophiles like H+ and PhCO+ to form diverse products via reaction of (COT)Fe(CO)3. Over 10 steps, several aminocycloheptitol compounds were synthesized in 15-26% overall yields. (3) The inhibitory activities of these compounds were tested against β-glucosidase. Several compounds showed IC50 values in the low micromolar to millimolar range, with one compound having an IC50 of 41.66 μM.

1. Generation Of Diverse Molecular Complexity
From Cyclooctatetraene
Marquette University
By
Mohamed El Mansy
04/03/2014

2. Diversity-oriented synthesis
 Preparation of structurally complex and
diverse compounds from simple starting
materials.
Lee, D.; Sello, J. K.; Schreiber, S. L. Org. Lett., 2000, 2, 709-712.

3. How to generate molecular
diversity?
 Reagent-based approach
Common starting material
 Substrate-based
approach
Common reagents
Diversity-Oriented Synthesis: Basics and Applications in Organic Synthesis, Drug Discovery, and Chemical Biology, 2013 John Wiley & Sons, Inc.

4. Cyclooctatetraene (COT)
 Simple compound C8H8.
 Commercially available.
Reppe, W.; Schichting, O.; Klager, K.; Toepel, T. Ann 1948, 560, 1-92. Barnes, C. E. U.S. Patent 2 579
106, 1951.
Shvo, Y.; Hazum, E. J. Chem. Soc., Chem. Comm. 1975, 829-830.

5. Reaction of (COT)Fe(CO)3 with electrophiles
El= H+
El= PhCO+
Broadley, K.; Connelly, N. G.; Graham, P. G.; Howard, J. A. K.; Risse, W.; Whiteley, M. W.; Woodward, P. J. Chem. Soc. Dalton
Charles, A. D.; Diversi, P.; Johnson, B. F. G.; Karlin, K. D.; Lewis, Rivera, A. V.; Scheldrick, G. M. J. Organomet. Chem.
1977, 128, C31-C34.
Davison, A.; McFarlane, W.; Pratt, L.; Wilkinson, G. J. Chem. Soc. 1962,
4821-4829.

6. Mechanism for formation
Broadley, K.; Connelly, N. G.; Graham, P. G.; Howard, J. A. K.; Risse, W.; Whiteley, M. W.; Woodward, P. J. Chem. Soc. Dalton
Charles, A. D.; Diversi, P.; Johnson, B. F. G.; Karlin, K. D.; Lewis, Rivera, A. V.; Scheldrick, G. M. J. Organomet. Chem.
1977, 128, C31-C34.
El= H+
El= PhCO+

7. Objectives

8. Glycosidic bond
 The glycosidic bond is very stable towards
hydrolysis.
 Glycosidase enzymes catalyze the hydrolysis
reaction. glycosidic linkage.
http://www.chem.qmul.ac.uk/iupac/2carb/33.ht

9. Glycosidase inhibitors
Hydrolysis of glycosidic bond with retention of configuration at anomeric carbon.
Zechel, D. L.; Withers, S. G. Acc. Chem. Res. 2000, 33, 11-18.

10. Examples of known aminocyclitols
Hooper, R. In “Aminoglycoside Antibiotics”; Umezawa, H., Hooper, I. R., Eds.; Springer, Berlin,
1981; p 7.
Girard, E.; Desvergnes, V.; Tarnus, C.; Landais, Y. Org. Biomol. Chem. 2010, 8,
5628–5634.
Casiraghi, G. et. Al. J. Org. Chem., 2003, 68, 5881-5885.

11. Aminocycloheptitols: Previous work
Casiraghi, G. et. Al. J. Org. Chem., 2003, 68, 5881-5885.
12 steps , overall yield is 23 %.
One optically pure compound

12. Girard, E.; Desvergnes, V.; Tarnus, C.; Landais, Y. Org. Biomol. Chem. 2010, 8,
Aminocycloheptitols: Previous work
11 steps , overall yield is 15 %
Racemic product

13. Our work
=2.73ppm=2.11ppm

14. 11 steps, 26% overall yield
11 steps , overall yield is 15 %
Racemic product
12 steps , overall yield is 23 %
One optically pure compound
Org. Biomol. Chem. 2010, 8, 5628–5634. J. Org. Chem., 2003, 68, 5881-5885.

15. Optically active tetraols


 


 



 

Anobick Sar

16. Optical purity

17. (>94% d.e.)
(>96% d.e.)
=6.22
ppm
=6.31
ppm

18. 11 steps, 15% overall
yield
11 steps, 12% overall

19. Bicyclic cyclitols
Kelebekli, L.; Kara, Y.; Balci, M.; Carbohydrate Res., 2005, 340, 1940-1948.
Kara, Y.; Balci, M. Tetrahedron, 2003, 59, 2063-2066.
Sengu, M.; Menzek, A.; Sahin, E.; Arik, M.; Saracoglu, N. Tetrahedron, 2008, 64, 7289–7294
Wang,Y.; Bennet, A. Org. Biomol. Chem., 2007, 5, 1731–1738

20. Synthesis of Bicyclicdiene

21. Exhaustive Dihydroxylation

22. Monohydroxylation

23. Fürst-Plattner Rule
Fürst, A.; Plattner, P. A. Helv. Chim. Acta 1949, 32,
275.
Disfavored by 5 Kcal/mol
Epoxide opens to trans diaxial

24. Epoxide ring opening

25. Epoxidation

26. Mechanism of Enone formation

29. Ring Expansion Mechanism

30. Formation of endoperoxide
Kishi model

31. Kornblum–DeLaMare
rearrangement

32. Preparation of
Epoxyendoperoxide

33. Ring Contraction

34. Proposed Ring Contraction
Mechanism

35. Generated Tetraols
 Out of 16 possible isomers, we synthesized 8.
 Assignments were made by NMR and single crystal X-ray
diffraction.

36. Testing of the generated
tetraols
 β-Glucosidase was selected as enzyme to be
initially testing the protected bicyclic tetraols.
 Validation of assay is done by using different
enzyme concentrations.
 Testing a known inhibitor and reproduce inhibition
data.
determined colorimetrically

37. Glucosidase Validation Curve
y = 0.0002x + 0.0132
R² = 0.9995
y = 2E-05x - 0.0028
R² = 0.9676
y = 0.0005x + 0.029
R² = 0.9991
y = 0.0009x + 0.0635
R² = 0.9984
y = 0.0012x + 0.0959
R² = 0.9974
y = 0.0022x + 0.1012
R² = 0.9989
y = 0.0017x + 0.1217
R² = 0.9993
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0 50 100 150 200 250
Absorbance(406nm)
Time (s)
Glucosidase Validation Curve
6…

38. Assay Results
-5 .0 -4 .5 -4 .0 -3 .5 -3 .0 -2 .5
7 0
8 0
9 0
1 0 0
1 1 0
M M L 2 8 6 _ f1 D o s e R e s p o n s e (4 p t)
lo g ([X ],M )
%Act
IC50=1.68mM
-5 .5 -5 .0 -4 .5 -4 .0 -3 .5 -3 .0 -2 .5
6 0
7 0
8 0
9 0
1 0 0
1 1 0
M M L 2 8 6 _ f2 D o s e R e s p o n s e
lo g ([X ],M )
%Activity
IC50= 156.8µM

39. -5 .5 -5 .0 -4 .5 -4 .0 -3 .5 -3 .0 -2 .5
7 0
8 0
9 0
1 0 0
1 1 0
M M L 3 2 6 _ f2 D o s e R e s p o n s e
lo g ([X ],M )
%Activity
IC50= 41.66µM
-5 .5 -5 .0 -4 .5 -4 .0 -3 .5 -3 .0 -2 .5
7 0
8 0
9 0
1 0 0
1 1 0
M M L 2 7 8 _ f2 D o s e R e s p o n s e
lo g ([X ],M )
%Act.
IC50= 1.904mM
Assay Results

40. -5 .5 -5 .0 -4 .5 -4 .0 -3 .5 -3 .0 -2 .5
7 0
8 0
9 0
1 0 0
1 1 0
M M L 2 9 2 _ f1 D o s e R e s p o n s e
lo g ([X ],M )
%Activity
IC50= 430µM
-5 .5 -5 .0 -4 .5 -4 .0 -3 .5 -3 .0 -2 .5
7 0
8 0
9 0
1 0 0
1 1 0
1 2 0
M M L 2 1 6 D o s e R e s p o n s e
lo g ([X ],M )
%Act.
IC50= 914.2µM
Assay Results

41. -5 .5 -5 .0 -4 .5 -4 .0 -3 .5 -3 .0 -2 .5
7 0
8 0
9 0
1 0 0
1 1 0
M M L 2 7 8 _ f2 D o s e R e s p o n s e
lo g ([X ],M )
%Act.
IC50= 1.904mM
-5 .0 -4 .5 -4 .0 -3 .5 -3 .0 -2 .5
6 0
7 0
8 0
9 0
1 0 0
1 1 0
1 2 0
M M L 3 1 6 _ f2 D o s e R e s p o n s e - T ria l II (4 -p t)
lo g ([X ],M )
%Act.
IC50=74.76µM
Assay Results

42. Formation of polycyclic structures
using olefin metathesis approach
M. F. El-Mansy , A. Sar , S. Chaudhury , N. J. Wallock and W. A. Donaldson , Org. Biomol. Chem.,

43. M. F. El-Mansy , A. Sar , S. Chaudhury , N. J. Wallock and W. A. Donaldson , Org. Biomol. Chem.,

44. Formation of polycyclic structures
using olefin metathesis approach
M. F. El-Mansy , A. Sar , S. Chaudhury , N. J. Wallock and W. A. Donaldson , Org. Biomol. Chem.,

45. Hoye, T.; Jeon, J.; Tennakoon, M. Angew. Chem. Int. Ed. 2011, 50,

46. Conclusion

47. Acknowledgment
Supervisor
Professor William A. Donaldson
Committee members
Professor Daniel Sem
Professor Chae S. Yi
Professor Christopher Dockendorff