Stereochemical Assignment Sheet

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Chirality Stereochemistry Cheat Sheet

Understanding chirality is important, not only to organic chemistry, but to understand the world around you in general. I like to think of chirality as ‘handedness’.

We have a right and left hand that are similar to each other, mirror images in fact. Yet our hands are not super-imposable. A right glove will not fit a left hand due to the opposite ‘handedness’.

Be sure to check out the Optical Activity Mini Series in Videos 8-10 below!

As you work through this series, pause and try each question and make sure you’ve mastered a topic before moving on.

Download my free Stereochemistry Cheat Sheet to follow along, and be sure to try the Stereochemistry Practice Quiz once you feel ready. Also, do you need a Model Kit? Watch How to Use Your Organic Chemistry Model Kit.

Video 1 – Introduction to Stereochemistry, Enantiomers and Chiral Molecules

Let’s start at the very beginning. WHAT is chirality? What does it mean for molecules? How can you identify a chiral carbon and what does that mean for its non-superimposable mirror image? All of this and more


Video 2 – R and S Configurations using Cahn-Ingold-Prelog rules

Now that you understand about chirality, how do you find it’s absolute configuration to see if it’s R or S? Learn how to rank substituents using the Cahn-Ingold-Prelog system and using priorities to differentiate between R and S stereoisomers.



Video 3 – Finding R and S When Group 4 is Forward

Finding R and S is easiest when priority group #4 is towards the back. But how do you find if a molecule is R or S when group #4 is facing forward? More importantly WITHOUT having to visualize a confusing 3-dimensional molecule? Learn how to use my ‘think backwards method’ and how I learned this in the military by watching video 3


Video 4 – Swap Method For Finding R&S Configurations

Swap Method Trick for quickly finding R and S configurations when group #4 not forward/back. Save time AND forget your model kit and mental molecule manipulations redrawing structures on your exam.



Video 5 – R & S Configuration for Lengthy Complex Substituents

This orgo tutorial video shows you how to approach lengthy and complex substituents so that you can quickly and easily determine R and S configurations.



Video 6 – Fischer Projection Stereochemistry Trick

This video shows you how to quickly and easily find R and S configurations directly on the Fischer Projection. Guaranteed to save you time on your next stereochemistry quiz/exam.



Video 7 – Newman Projection Stereochemistry R&S Trick

This video teaches you how to quickly find configurations of molecules presented in a Newman Projection. Learn how to view the molecule and quickly assign priority WITHOUT the need to redraw into a sawhorse projection.



◊ Optical Activity in Stereochemistry Mini-Series ◊

Video 8: Polarimetry

Each enantiomer of a chiral molecule has its own characteristic of light rotation! And not to be confused with R/S!!

This video introduces polarimetry, racemic mixtures vs pure solutions, +/- , dextrorotary (D) and levorotary (L), and more.

Video 9: Specific Rotation

This video details the factors influencing specific rotation such as observed rotation, g/mL, path-length, wavelength, and temperature. Along with test-level examples!



Video 10: Enantiomeric Excess Percentage and Optical Purity

This video shows the logic behind EE% or Enantiomeric Excess Percentage, also known as Optical Purity Percentage. Step by step example calculations are shown and more.

Additional Chirality Videos to Follow

Don’t forget to Download my free Stereochemistry Cheat Sheet to remember all the details and be sure to try the Stereochemistry Practice Quiz to test your skills!

1. De Caterina, R., S. Endres, S.D. Kristensen, and E.B. Schmidt. 1993. N-3 Fatty Acids and Vascular Disease. Bi & Gi Publishers, Verona. 166 pp.

2. GISSI-Prevenzione Investigators. 1999. Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Lancet.354:447–455. [PubMed]

3. Albert, C.M., H. Campos, M.J. Stampfer, P.M. Ridker, J. Manson, W.C. Willett, and J. Ma. 2002. Blood levels of long-chain n-3 fatty acids and the risk of sudden death. N. Engl. J. Med.346:1113–1118. [PubMed]

4. Weiss, U. 2002. Insight: inflammation. Nature.420:845–891.

5. Funk, C.D. 2001. Prostaglandins and leukotrienes: advances in eicosanoid biology. Science.294:1871–1875. [PubMed]

6. Rowley, A.F., D.J. Hill, C.E. Ray, and R. Munro. 1997. Haemostasis in fish, an evolutionary perspective. Thromb. Haemost.77:227–233. [PubMed]

7. Serhan, C.N., C.B. Clish, J. Brannon, S.P. Colgan, N. Chiang, and K. Gronert. 2000. Novel functional sets of lipid-derived mediators with antiinflammatory actions generated from omega-3 fatty acids via cyclooxygenase 2-nonsteroidal antiinflammatory drugs and transcellular processing. J. Exp. Med.192:1197–1204. [PMC free article][PubMed]

8. Serhan, C.N., S. Hong, K. Gronert, C.P. Colgan, P.R. Devchand, G. Mirick, and R. Moussignac. 2002. Resolvins: a family of bioactive products of omega-3 fatty acid transformation circuits initiated by aspirin treatment that counter proinflammation signals. J. Exp. Med.196:1025–1037. [PMC free article][PubMed]

9. Clish, C.B., J.A. O'Brien, K. Gronert, G.L. Stahl, N.A. Petasis, and C.N. Serhan. 1999. Local and systemic delivery of a stable aspirin-triggered lipoxin prevents neutrophil recruitment in vivo. Proc. Natl. Acad. Sci. USA.96:8247–8252. [PMC free article][PubMed]

10. Lawrence, T., D.A. Willoughby, and D.W. Gilroy. 2002. Anti-inflammatory lipid mediators and insights into the resolution of inflammation. Nat. Rev. Immunol.2:787–795. [PubMed]

11. Tessier, P.A., P.H. Naccache, I. Clark-Lewis, R.P. Gladue, K.S. Neote, and S.R. McColl. 1997. Chemokine networks in vivo. Involvement of C-X-C and C-C chemokines in neutrophil extravasation in vivo in response to TNF-α. J. Immunol.159:3595–3602. [PubMed]

12. McMahon, B., S. Mitchell, H.R. Brady, and C. Godson. 2001. Lipoxins: revelations on resolution. Trends Pharmacol. Sci.22:391–395. [PubMed]

13. Yokomizo, T., T. Izumi, K. Chang, Y. Takuwa, and T. Shimizu. 1997. A G-protein-coupled receptor for leukotriene B4 that mediates chemotaxis. Nature.387:620–624. [PubMed]

14. Gewirtz, A.T., L.S. Collier-Hyams, A.N. Young, T. Kucharzik, W.J. Guilford, J.F. Parkinson, I.R. Williams, A.S. Neish, and J.L. Madara. 2002. Lipoxin A4 analogs attenuate induction of intestinal epithelial proinflammatory gene expression and reduce the severity of dextran sodium sulfate-induced colitis. J. Immunol.168:5260–5267. [PubMed]

15. Samson, M., A.L. Edinger, P. Stordeur, J. Rucker, V. Verhasselt, M. Sharron, C. Govaerts, C. Mollereau, G. Vassart, R.W. Doms, and M. Parmentier. 1998. ChemR23, a putative chemoattractant receptor, is expressed in monocyte-derived dendritic cells and macrophages and is a coreceptor for SIV and some primary HIV-1 strains. Eur. J. Immunol.28:1689–1700. [PubMed]

16. Kopp, E., and S. Ghosh. 1994. Inhibition of NF-κB by sodium salicylate and aspirin. Science.265:956–959. [PubMed]

17. Wittamer, V., J. Franssen, M. Vulcano, J. Mirjolet, E. Le Poul, I. Migeotte, S. Brezillon, R. Tyldesley, C. Blanpain, M. Detheux, et al. 2003. Specific recruitment of antigen-presenting cells by chemerin, a novel processed ligand from human inflammatory fluids. J. Exp. Med.198:977–985. [PMC free article][PubMed]

18. Methner, A., G. Hermey, B. Schinke, and I. Hermans-Borgmeyer. 1997. A novel G protein-coupled receptor with homology to neuropeptide and chemoattractant receptors expressed during bone development. Biochem. Biophys. Res. Commun.233:336–342. [PubMed]

19. Endres, S., R. Ghorbani, V.E. Kelley, K. Georgilis, G. Lonnemann, J.W. van der Meer, J.G. Cannon, T.S. Rogers, M.S. Klempner, and P.C. Weber. 1989. The effect of dietary supplementation with n-3 polyunsaturated fatty acids on the synthesis of interleukin-1 and tumor necrosis factor by mononuclear cells. N. Engl. J. Med.320:265–271. [PubMed]

20. Aliberti, J., S. Hieny, C. Reis e Sousa, C.N. Serhan, and A. Sher. 2002. Lipoxin-mediated inhibition of IL-12 production by DCs: a mechanism for regulation of microbial immunity. Nat. Immunol.3:76–82. [PubMed]

21. Nathan, C. 2002. Points of control in inflammation. Nature.420:846–852. [PubMed]

22. Topper, J.N., J. Cai, D. Falb, and M.A. Gimbrone Jr. 1996. Identification of vascular endothelial genes differentially responsive to fluid mechanical stimuli: Cyclooxygenase-2, manganase superoxide dismutase, and endothelial cell nitric oxide synthase are selectively up-regulated by steady laminar shear stress. Proc. Natl. Acad. Sci. USA.93:10417–10422. [PMC free article][PubMed]

23. Cheng, Y., S.C. Austin, B. Rocca, B.H. Koller, T.M. Coffman, T. Grosser, J.A. Lawson, and G.A. FitzGerald. 2002. Role of prostacyclin in the cardiovascular response to thromboxane A2. Science.296:539–541. [PubMed]

24. Serhan, C.N. 2002. Endogenous chemical mediators in anti-inflammation and pro-resolution. Curr. Med. Chem.1:177–192.

25. Chiang, N., I.M. Fierro, K. Gronert, and C.N. Serhan. 2000. Activation of lipoxin A4 receptors by aspirin-triggered lipoxins and select peptides evokes ligand-specific responses in inflammation. J. Exp. Med.191:1197–1207. [PMC free article][PubMed]

26. Perretti, M. 2003. The annexin 1 receptor(s): is the plot unravelling? Trends Pharmacol. Sci.24:574–579. [PubMed]

27. Gronert, K., S.P. Colgan, and C.N. Serhan. 1998. Characterization of human neutrophil and endothelial cell ligand-operated extracellular acidification rate by microphysiometry: impact of reoxygenation. J. Pharmacol. Exp. Ther.285:252–261. [PubMed]

28. Capdevila, J.H., S. Wei, C. Helvig, J.R. Falck, Y. Belosludtsev, G. Truan, S.E. Graham-Lorence, and J.A. Peterson. 1996. The highly stereoselective oxidation of polyunsaturated fatty acids by cytochrome P450BM-3. J. Biol. Chem.271:22663–22671. [PubMed]


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