Synthesis of Essential Intermediate

4H-Seleno[3,2-b]pyrroleJacob Curry

Synthesis Aim

Figure 1: 4H-Seleno[3,2-b]pyrrole

Figure 2: 4H-Seleno[3,2-b]pyrrole compared with [4,5]selenotryptophan.

BackgroundProteins and amino acids—what’s so

important?

• Form and function

• Mutations in sequence

Figure 3: Arabinose binding protein.Image from http://chemistry.umeche.maine.edu/

X-Ray Crystallography and NMR• Accurately shows

structural themes for

observed molecules

• NMRo Not crystal-based

o No size restriction

Figure 4: X-ray crystallography method.Image from http://projectcrystal.org/

The Phase Problem and MAD

• The images developed by X-ray

crystallography have scattering issues.

• Inclusion of a heavy atom/metal eliminates

the problem and helps elucidate protein

structure.

• Multi-wavelength Anomalous Dispersiono Scattering of electron-rich metalloid atoms

o Thus, phase may be determined by a single species

Methods• Paulmier-Phillips Protocol vs. Boles-Silks-

Hatch Method

• Why?

oCost-efficient, reaction timeline

oStable product

oDirect 77Se insertion

• Mass spectroscopy, NMR

• Past experiences

Paulmier-Phillips Scheme

Figure 5: Paulmier-Phillips scheme.

21

34

Boles-Silks-HatchScheme

Figure 6: Boles/Silks/Hatch scheme for the synthesis of 4H-seleno[3,2-b]pyrrole.

21

3

4

Product % Yield Mass (g)

2 98.8 % 1.446

3 47.6% 0.632

4 In progress

/

Step 1: Bromination

Product % Yield Mass (g)

2 98.8 % 1.446

Step 2: Transmetallation

Product % Yield Mass (g)

3 47.6 % 0.632

Step 3: Annulation

Product % Yield Mass (g)

4 In prog. /

Overall…• Each step of the scheme has been verified

and has produced in good yield

• Efficiently developing and purifying this

product in a favorable yield is essential to the

synthesis of [4,5]selenotryptophan

• Artificial amino acids/analogs

oDetermine protein form and function

oProtein-based drugs/treatments

Future Work• Scale up the reactions

• Continued purification

• Reach conclusion of this scheme: 4H-

Seleno[3,2-b]pyrrole

• Do scheme with tellurium (Te)

• Follow this up with synthesis of final analog

[4,5]selenotryptophan

Lignin Peroxidase• Peroxidases break

down lignin

• Contains a catalytic tryptophan domain, Trp 171

• Gain an understanding of the enzyme and its mechanism

Figure 7: Lignin peroxidase.

References• Hatch, Duane M. et al. Methods for the Synthesis of Heavy-Atom Derivatized Amino

Acids: Useful Probes for X-Ray Crystallography, Vibrational, and NMR Spectroscopy of

Proteins. Current Organic Chemistry, 2004, 8, 47-64. Print.

• Hatch, Duane. Novel Synthesis, Purification, and Characterization of Labeled and

Unlabeled (6,7) Selena-L-Tryptophan and It’s Potential Use in the Elucidation of Protein

Structure and Function. Tenn. Tech. Univ. 2003. pp. 4-8, 19-70. Print.

• Hatch, Duane. Towards a Concise Annulation Method for the Synthesis of Selenolo[2,3-

b] and [3,2-b]pyrrole and Further Enzymatic Elaboration to Labeled and Unlabeled

[6,7]SeTrp and [4,5]SeTrp. Print.

• Nelson, D., & Cox, M. Lehninger Principles of Biochemistry (6th ed.). New York: W.H.

Freeman and Company, 2013. 15, 89, 143, 576, 906-907. Print.

• Pecorino, L. (2012). Apoptosis: Molecular Mechanisms of Apoptosis. In Molecular

Biology of Cancer (3rd ed.). Oxford: Oxford University Press.

• Pecorino, L. (2012). DNA structure and stability: Mutations versus repair. In Molecular

Biology of Cancer (3rd ed.). Oxford: Oxford University Press.

• Read, R. (2008, April 22). Overview of macromolecular X-ray crystallography. Retrieved

April 18, 2015, from http://www-

structmed.cimr.cam.ac.uk/Course/Overview/Overview.html.

Thanks• Duane Hatch, Ph.D.

• Ryan Agh

• Daniel Gilani

• Belmont University

oCollege of Sciences and Mathematics

oDepartment of Chemistry and Physics

• Los Alamos National Laboratories, Bioscience Division

• Department of Energy VFP