Organic Chemistry II (CHE 232-002) Final Examination April 30, 2007 Name (Print legibly):___________________________ (last) (first) PLEASE observe the following: You are allowed to have scratch paper (provided by me), and a simple model set. You do not need a calculator. Please have your student ID card present on your desk. Read through the entire exam before beginning and start first on the problems that seem easiest to you. Please provide clear and concise answers to the questions in the area provided, the back of an exam page, or on the clearly labeled spare page. Problem Score 1 /60 2 /20 3 /16 4 /60 5 /45 6 /20 Total /200IIIIIIV1 1. (5 pts each, 60 pts total) Draw the major product of each of the following reactions. Do not draw mechanisms! If no reaction occurs, write N.R. (a)(b)(c)(d)(e)CH3MgBrH3OOCCH3CH2OH+ SOCl2OCCH3CH2OCCH3O+ CH3NH2excessCOOCH3OCCH3CH3H2/Pt NH3OCH3CH3NaBH4H2OPBr3OCCH3CH2ClOCCH3CH2NH(CH3)COHCH3CH3BrCH3CH3NH2CHCH3CH32 (f)(g)1. OH–/H2O, refluxOCCH3OCH2CH32. HCl(h)OCH2CH3H3CO+1. OH–2. H3O+/ heatO1. CH3MgBr2. H3O+1. Ph2CuLi2. H3O+(i)COOHSOCl2AlCl3H2/PtOCCH3OH+ CH3CH2OHOHCH2CH3H3COOHCH3OPh3 (j)CH3CH2CH2BrNaOH/H2OPCCHNO3, H2SO4H3C C ClOAlCl3(k)HOCOCH3NO2 2. (5 pts each, 20 pts total) Provide the reagents needed to convert the starting materials shown into the products shown. Br(a)(b)OCO2Et(c)OEtOOH CO2H(d)CO2HON1. Ph3P2. BuLi3.OCrO3, H2SO4/H2OorNa2Cr2O7, etc.1. NaOEt (cat)2. H3O+1. SOCl22. Et2NH4 3. (16 points) (a) (8 pts) Of the carboxylic acid derivatives shown below, circle and label the MOST reactive acylating agent, AND circle and label the LEAST reactive acylating agent. OClOOEtONH2OOOMost ReactiveLeast Reactive (b) (8 pts) Explain why cation A is much less stable than cation B. NNMe:MeAB A is not aromatic while B is aromatic. Complete delocalization in B allows for greater resonance stabilization of the cation in comparison to A.5 4. (60 points) Design syntheses of the three compounds below from the indicated starting materials. Show how you would prepare each product from the indicated starting material(s). Each synthesis will require two or more steps. Show each intermediate compound and all the reagents you will need for each step. (Don’t panic if you can’t remember the reagents for a particular step; partial credit will be given.) Do not show reaction mechanisms. (a) Ostarting materialForward reaction:OHOKMnO4SOCl2ClO1. Et2CuLi2. H2OO6 (b) OBrstarting materialOClOLiCu2+COOHCNBrBrRetrosynthesis, one possibilityForward:Br1. CuBr2. BuLiLiCu2BrKCNCNH3O+COOHSOCl2ClOLiCu21.2. H2OO7 (c) OHHOHOOBr+starting materialsForwardHOBrHOOH, H3O+HOBrMgOMgO1.2. H2O, H3O+OHHOHOBrO8 4. (45 points) Draw a reasonable stepwise mechanism for each of the following reactions. Be sure that you show every bond making/bond breaking event and be sure that your use of arrows conforms to established conventions. (a) (15 pts) NaOH, H2OOMeOMeOOO+ See Textbook9 (b) (15 pts) HClH2OPh C NPhCNH2O Ph C NPh C N H••OHH••••PhCONHHHCl–PhCONHHH Cl••H ClPhCONH2HPhCONH2HCl–PhCNH2O••••10 (c) (15 points) COHCl, Cl2, H2OCOCl11 6. (20 points) (a) (10 pts) Shown below is the 1H NMR spectrum for a compound whose molecular formula is C10H12O2. An infrared (IR) absorption for the compound is found at 1740 cm-1. aromatic H'sHb'sHa'sCH3 Which of structures A-D is most plausible for the compound? Assign the 1H NMR spectrum by labeling appropriate groups of chemically equivalent hydrogen atoms in the structure that you have chosen and correlate your labels with the 1H NMR spectrum. AO CH3OOOOOOOCBDHaHaHbHb12 (b) (10 pts) In each problem below, choose one method (optical activity, MS, IR, 1H NMR, or 13C NMR) that will allow you to unambiguously distinguish between the two compounds. Precisely describe the difference that you expect to see in spectra of the two compounds that will allow you to distinguish between the two compounds (correct description of the difference in the spectra is worth 4 points). Be brief (no more than two sentences). (i) OHCO2EtClOHCO2EtClAB Method for distinguishing: 1H NMR Difference: Only in A does one of the aromatic protons show as a singlet. (ii) OHClOHClCD Method for distinguishing: 1H or (proton-coupled) 13C NMR spectra Difference: Only in the 1H NMR spectrum of C does a doublet resonance (for isopropyl methyls) and a septet (for isopropyl methine (CH) proton) appear. Only in the proton-coupled 13C NMR spectrum of C does a doublet resonance appear in the alkyl region (0-50 ppm) for isopropyl methine (CH)
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