Examine the HSQC-TOCSY spectra with 5, 10, 20, and 100-ms mixing times. Numbers associated with the 13C resonances associated with the C-ring spin system: _, _.Ĭ. Numbers associated with the 13C resonances associated with the B-ring spin system: _, _, _. Numbers associated with the 13C resonances associated with the A-ring spin system: _, _, _. Methylene resonances are associated with the three main spin systems in the molecule, which we willĬall the A-ring spin system, the B-ring spin system, and the C-ring spin system: Methylene groups, it is easy to identify the methine groups.Įxamine the HMQC spectra and correlate the numbers of 13C resonances with the letters of the 1Hįinally, examine the HSQC-TOCSY spectrum with 100-ms mixing time and identify which methine and NOTE: Although the DEPT 90 contains small resonances associated with the methyl and Examine the 13C NMR spectra and number the sixteen unique resonances associated withĮxamine the DEPT spectra and identify the quaternary (C), methine (CH), methylene (CH2), and methyl Examine the 1H NMR spectra and familiarize yourself with the resonances, which have been letteredĪ–l for you. Ring, please see my course web page "Perhydroanthracenes" and the associated. If you would like to seeĪn example of a related exercise in which ring fusion induces a twist boat conformation in a cyclohexane pdb files of boat and twist-boat cyclohexane, which can be opened in PyMOL. If you would like to review the conformations of cyclohexane, please see my Chem H52A course web The A–B ring junction will look like that of the otherĭiasteromers, but the B–C ring junction will be enforcing a twist-boat conformation of the B ring. Ring junction does not allow the B ring to adopt a chair conformation. NOTE: For diastereomer 4 you will have to build the B ring in a boat conformation, because the B–C You are also welcome to just make your own trans-decalin. pdb file on the course web page "SimpleĬonformational Analysis of Cyclic and Bicyclic Compounds" which is linked to the "Assignments" and pse files as diastereomer1.pse,ĭiastereomer2.pse, diastereomer3.pse, and diastereomer4.pse.įeel free to use the trans-decalin template. Quality with (Display-Quality-Maximum Quality). Use the pulldown menu to display each molecule in maximum Use the side menu (S) to showĮach molecule as sticks (Show-sticks). Rotate each molecule into an appropriate orientation. Build energy-minimized molecular models of diastereomers 1, 2, 3, and 4 using PyMOL and the MAKE SURE TO COMPLETELY ANSWER THE QUESTIONS a-g ON PAGES 2-6.Ī. With squiggly lines, and hence which of the four possible diastereomers (1, 2, 3, or 4) is consistent with
Specifically, assign the stereochemistry of the two stereocenters shown Using these data, determine the stereochemistry and assign all of the 1H and 13C resonances to their All NMR spectra were measured in C6D6 solution. The following spectral data are provided for a tricyclic compound: 500.22 MHz 1H NMR, 125.79 MHzġ3C NMR, DEPT, COSY, TOCSY, HMQC, HMBC, NOESY, and HSQC-TOCSY spectra with 5-, 10-,Ģ0-, and 100-ms mixing times.
GRADE (F) IN THE CLASS, AND MAY RESULT IN EXPULSION FROM THE Ph.D. SUCH ITEMS CONSTITUTES ACADEMIC DISHNONESTY, WILL RESULT IN A FAILING Catalogs of molecular structures (e.g., the Aldrich catalog, the Merck Index,Įtc.) or databases of molecular structures (such as wireless access to SciFinder Scholar, the Sigma-Īldrich website, etc.) are NOT PERMITTED. Communication with other students by e-mail, text, or Wired) internet access and appropriate software (e.g, PyMOL, Maestro/MacroModel, Excel,ĬhemDoodle, Chemdraw, ElComp, MolE, etc.). If you wish to unstaple the pages, please initial each page.īooks, notes, lecture videos, calculators, rulers, and laptop computers are permitted as is wireless (or ONLY THE FIRST TWO (Part II, PROBLEMS 1-2) WILL BE GRADED IF THREE PROBLEMS FROM PART II ARE SUBMITTED, Nowick, Professor of Chemistry, University of California, Irvine, is licensed under a Creative Commons Attribution 4.0 International License.ĪND TWO OUT OF THE THREE PROBLEMS FROM PART II
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