215 Exam-00-2 - Chemistry 2 1 5 Second Examination February...

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Unformatted text preview: Chemistry 2 1 5 Second Examination February 22, 2000 Name Please Print Dr. Edwin Vedejs (Sec 100) Dr. Masato Koreeda (Sec 300) (1.5 hr; 120 points) Signature Student ID # Please CHECK OFF your 216 Lab section. _101 Lecture ONLY _311 M 1-5 PM A624 CHEM SCHACH, ANDREW -110 M 1-5 PM A606 LARSEN, AMY _312 M 1-5 PM A642 CHEM CA0, GANFENG _111 M 1-5 PM A612 CHEM CLARKE. NAGASH _330 T 1-5 PM A636 CHEM STAY, PATRICK _130 T 1-5 PM A606 CHEM CHEN. BIN _331 T 1-5 PM A642 CHEM SCHEIDEMAN, MATTHEW _131 T 1-5 PM A612 CHEM CLAY. JULIA _332 T 1-5 PM A730 CHEM POCN, STEVE _132 T 1-5 PM A618 CHEM SMALL, AARON _333 T 1-5 m A735 CHEM TAN, L1 -133 T 1-5 PM A624 CHEM ZHANG. BO _334 T 1-5 PM A742 CHEM ZHENG, NAN _134 T 1-5 PM A630 CHEM DENSMoRE, CRYSTAL _350 w 12-4 pM A536 CHEM SCHACH, ANDREW _150 w 12-4 PM A606 CHEM LARSEN, AMY _351 w 12-4 PM A642 CHEM CA0, GANFENG _151 w 12-4 PM A612 CHEM TURPOFF, ANTHONY _352 w 1-5 m A524 CHEM KOMAZTN, GLORIA _152 W 12- 4 PM A618 CHEM ZHANG. LIMING _353 w 1-5 PM A630 CHEM DENSMCRE, CRYSTAL _170 TH 1-5 PM A606 CHEM CHEN. BIN __354 w 1-5 PM A742 CHEM HANN, CLAYTON _171 TH 1-5 PM A612 CHEM CLAY, JULIA _370 TH 1-5 PM A636 CHEM STOY, PATRICK _172 TH 1-5 PM A618 CHEM TUPPOFF. ANTHONY _371 TH 1-5 PM A642 CHEM SCHEIDEMAN, MA'I'I'HEW _174 TH 1-5 PM A624 CHEM HANN. CLAYTON _372 TH 1-5 PM A730 CHEM POON, STEVE _190 F 1-5 PM A606 CHEM ZHANG, BO _373 TH 1.5 PM A736 CHEM TAN, L1 _191 F 1-5 PM A612 CHEM CLARKE, NAGASH _374 TH 1.5 pM A742 CHEM ZHENG, NAN .301 Lecture ONLY _390 F 1-5 PM A618 CHEM ZHANG, LIMING _310 M 1-5 PM A618 CHEM SMALL. AARON _391 F 1-5 PM A624 CHEM KOMAZIN, GLORIA The exam has 11 pages in addition to this cover page. The last 3 pages include tables of pKa values for representative acids, electronegativity values for some elements, and bond dissociation energies for representative bonds, and a list of reagents. Individual point values are given in the comer of each answer space. GSI Initial PERIODIC CHART OF THE ELEMENTS I n 1.00794 3 4 mm 6.941 9.01215 5 a 7 B 10 C N 0 Ne 10.81 12.011 14.0067 15.9994 :23: 0: 20,179 13 14 15 1s 17 18 H Al Si P S Cl Ar r/ ::-: .31 28.085 .9376 32.06 35.453 39.948 19 20 21 22 23 26 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc T1 Fe Co Ni Ga Ge As Se Br Kr ---:( 40.03 44.9559 47.38 50.9015 51.996 -- 5 1" 55.347 58.9332 58.69 63.546 65.38 69.72 72.59 4.9216 78.96 79.904 83.80 37 38 39 40 41 {2 43 44 45 46 ‘5 50 51 52 54 Rb Sr Y Zr Nb Mo Tc Ru E Cd Sn Sb Te Xe 854678 87.62 33-9059 91.2 92.964 95.94 (98) 101.07 (2 3'“ 10612 =-‘=’n 112.41 118.69 121.75 127.80 5- 131.29 55 56 57 504‘ 72 73 76 75 76 77 7a 79 BO 31 82 83 84 35 56 CS Ba La mm.- Hf E W Re Os Ir Pt Au Hg TI Pb Bi Po At Rn :nsoa 137.33 u- ' IDES 175.49 130947910335 186.207 190.2 19222 19503 196.200.59 04.333 207.2 I: (209) (210) (222) 87 BE 89 90403 104 105 106 107 '1 '5 111 112 Fr Ra Ac Am. R1 DD 89 Bh Hs (22;) 2252711273 IDES (251) (262) (233) 58 59 50 B1 63 6‘ 65 65 G7 68 69 7O 71 EEHENEEHEHEEHEHH 140.12 140 144.24 (145) 151.96 58. ~ 158.9 162.50 '01 167.26 mm 173.04 174.967 90 91 D4 95 96 97 98 100 101 102 103 Henennama a awmu ‘vv‘l¢~.: 4: was x n:- . (2“) (243) (247) (247) (251) (29) (258) (259) (260) V 10 13 II mwlnll VIII (3) 0 1 120 Page 1. Name I (13 points) For each of the following pairs of compounds, predict which compound is the more acidic. Compare the two underlined protons for each pair. The more acidic compound for each pair will be (circle one): II (1) (9 points) The pKa values for the conjugate acids of meta- and para—acetylaniline are shown in the box below. Match the pKa values with the corresponding conjugate acids. + O N_H_3 pKa 2.19 is: H3C pKa 3.56 is: O a. meta-isomer b. para-isomer H30 Explain your answer by clearly drawing in the box given below the relevant resonance structures and by providing a brief explanation. K153 + Nfls H30 H C . 3 meta—1 r . 0 some para-1somer Page 2. Name II (2) (8 points) a. The pKa value of the conjugate acid of acetamidine is considerably higher (12.40) than that of a typical imine (estimated to be around 5—7). Explain this difference in pKa values using resonance structures of the conjugate acids. £1 H30 N'Hz acetamidine it H3C CH3 an imine I 4 b. The pKa values of the conjugate acids of N,N—dimethylaniline and pyridine are, respectively, 5.1 and 5.25. The pKa value of the conjugated acid of 4—(N,N-dimethylamino)pyridine is about 10. Explain why the pKa value of the conjugate acid of 4-(NJV-dimethylamino)pyridine is considerably higher by drawing resonance structures of the conjugate acid of 4—(N,N—dimethylamjno)pyridine in the box given below. .. / / .. QMCHQZ :N \ :N \ N(CH3)2 N, N-dimethylaniline Pyridine 4-(N,N—dimethylamino)pyridine Page 3. Name III. (14 points) Consider the following structures: (a) 8 (b) H l? H—C—OC(CH3)3 H—CCHgC—OCH3 I? “3? I? (C) CH3CH20—OCH3 (d) H20=C—C—OCH3 (1). Which of the above can form an enolate in the presence of N a+ ‘OCH3? Note: minus 2 points for a wrong answer. (2). Which two of the above would react with each other to form structure 1 when treated with Na‘“ OCH3? ?' “‘“9 CH3 1 Page 4. Name IV. (10 points) The non-prescription painkiller Ibuprofen (Nuprin, Advil, Motrin, etc.) is sold as mixture of 2 and 3 (1 : 1 ratio). H Ar .3 CH3, I CH3, I ,OH /0\ /OH Ar: /f©/ H I o CH3HCH3 2 3 0 (1). What is the relationship between 2 and 3? (circle one answer in the box below). enantiomers diastereomers conformers (2). It is known that 2 is the active drug. However, 3 is also effective because liver enzymes convert 3 into 4 and then to 5 in a reversible reaction. Hydrolysis of 5 occurs to give 2. Ar - Ar H CH3” I Ilver CH3” I CH3 / 0\ /OH enzymes /C\ /SR "Ox /SR H/ C H + Ar/ H fi fi -SR = Coenzyme A O O O 3 4 5 (enzyme cata|yst) H20 Suggest an intermediate that explains reversible conversion from 4 to 5. You may assume acid catalysis g base catalysis (specify which). CH CH3“. / catalyst 30 I H/C\Cf/SR Z r/C\ /SR | | 4 O 5 O Page 5. Name A number of reactions discussed in the class have been used in recent syntheses of natural products or biologically active compounds. In each of the questions V - VIII, supply the structure of the intermediate, product, or the reagent(s) in the box provided. When stereochemistry is known, please show it in the structural formulas you use. When a racemic mixture forms, show the stereochemistry of one enantiomer and write "and enantiomer” in the box. V. (20 points) Intermediates for the synthesis of cassiol were prepared by the sequence shown below (Tetrahedron: Asymmetry 1999, 10, 3189). O + L‘ /CH(CH3)2 CHSI '\ - 78 °C CH(CH3)2 CH30CH20 1) 2) CH3); CHZOH a base an electrophile CH3 CHZOH o " cassiol O (for information only) CH300H20 and enantiomer Page 6. Name VI. (13 points) Structure 8 can be made by an aldol cyclization from 6 (J. Org. Chem. 1999, 64, 7412). Draw structures of 6 and 7 and the reagent(s) needed for the conversion to 8. reagents(s) 6 (C11H1602) 7: an aldol longer reaction If you are not sure of 7, draw the complete structure of “me any simple aldol below: CH3 (won't be graded if 7 is correct) VII. (10 points) The following reactions were carried out as part of the preparation of a chiral diol (structure 9) (Synth. Commun. 1999, 29, 3829). if c\ l? OCgHs + /C\ 3 Bl'( CH2) OC2H5 KH 9 (for your information only) HCI + C02 H20 (solvent) A 09H14Os (hint: The last product contains a carboxylic acid group.) Page 7. Name VIII. (23 points) Show the structure of the major product for each of the following reactions. (1). Synthesis of spirocyclic model compounds related to the antitumor antibiotic neocarzinostatin chromophore (Org. Lett. 1999, I, 1375). o 1. 03; 2. (CH3)23 N32C03 <-———— dimethylformamide (solvent) and enantiomer (2). Synthesis of highly functionalized steroid nuclei (Synlett. 1999, 1491). o w + 80 °c II'IO Br 0 endO-adduct Page 8. Name VIII. (continued) (3). Investigation of a new Diels-Alder reaction (J. Org. Chem. 1999, 64, 3039). TBDMS -70°C \ + I@ _. O N CH5’ \CH3 endO-adduct TBDMS \ + q: 80°C 0 O N CH5’ \CH3 endO-adduct ACID pKa CONJUGATE BASE * (Strongest Acid) (Weakest Base) 3?. . a? ... e Hd—fi-QH _9 HQ—fi—Q : -.°.- '9.- - .--.e H—!. _9 . 1.. .. .. G) H-g: _7 :91: 7g - . . o. CH;CHz/O\H .24 CHsCHz’ \H T .° 6) :0’. o (If. . O'lolooa G) eibFN‘5H -1.3 aofN‘iite .‘O'. :0 g . ” 9 03C] \9H 0.64 asc/ H—E—ft 32 :E:9 .‘o'. .6. g g e g ‘9” 4.2 0 ‘§: /H H / [H H C e \\ /. </ \\,C 4-H 4.6 _ C_N\‘ _. I H H 0°~ ' 0' ” g\..e CH3/C\§5H 4.8 CH3/ 2 .‘o'. ’0" ” .. E .. e H6{c\'du 6.5 HQ’ ‘9: '0' 0 ..fi . . ICOII E. C C / \ / \ cur :c:H\cn3 9-2 ca: 3,99 ca; H-CEN‘ 9_1 exam if! 6) IH H-N—H 9.4 H-N\' é u I” [H c C </ “,C-ICEH 10.0 / \‘C-IOE G Page 9 ACID pKa CONJUGATE BASE ” 0.0.. .IOQ‘ " :4 e ‘5 0§C\:0H 10.2 950; \g; "0" .'O'. “6) n H . 6:6"qu 10.2 @--,N§>C-.e " H H ‘ . H/ \H .9 CH3CHZ/ \H CH3CH2—S.. 30“ :0. pk /“ 15 o ” CH3/ If: - CH3/C\if':e H H HI.0\H 15.7 H-{D' :6 'CHSCHZ/‘Om 17 CH3CH2—Eé:e c H c . e / \ I 19 / \ . CH3 H/C\H CH3 H/C\H 9 an cx—(l:—H 20 C1_ (I: e C' a H—CEC-H H...c-=-C :6 6) H2 35 H : 5*. . fie H/I... H\ e H H C=c: ,‘C=C; 36 H/ \H H H / c’H / ll CE: 41 \ l I \ ,RH H H H 0.9 43 H *3 *fi H—c-H 49 H—(‘ZIG A H (Weakest Acid) (Strongest Base) Page 10 Table 1.2 Electronegativity Values for Some Elements Table 2.4 Average Bond Energies [kJ/mol (above) and kcal/rnol (belown Single Bonds C=O (aldehydes) 176 749 C=O (keloncs) 179 Page 11 The Reagent List Shown below is a list of key reagents (not always the whole recipe) which may be useful for solving questions on the exam #2. Reagent classification or specialized use Chapter 13 NaBH4 nucleophilic hydride LiAlI-L nucleophilic hydride RMgX nucleophilic carbon RLi nucleophilic carbon Raney Ni desulfurization HSCHZCHZSH thiacetal/thioketal formation 4—CH3C61-LSO3H (TsOH) organic-soluble acid CSHSNH+ ClCrO3' oxidant ClC(O)C(O)Cl/H3CS(O)CH3 then (CH3CH2)3N oxidant HZNNH2 hydrazone formation HZNOH oxime formation BF3°O(CH2CH3)2 Lewis acid source (CH3)3C(CH3)QSiCl (TBDMS—Cl) protection H 39 9H3 H gC-Q-$i-Cl H3O CH3 (CH3CH2CH2CH2)4N+F‘ nucleophilic F source dihydropyran (CngO) protection 0 0 Chapter 14 AgZO, NaOH, H20 oxidant Chapter 15 (C4Hg)2AlH (DIBAL) Lewis-acidic hydride source Chapter 17 KB base LiN[CH(CH3)2]2 strong base Historical HZNNHC(O)NH2 For 216 labs; not for 215 exams HZNNHC6H3(NOZ)2 For 216 labs; not for 215 exams From Chem 210 0504 oxidation KMnO4 oxidation peroxyacid (e.g., 3—chloroperoxybenzoic acid) oxirane formation 03 then (CH3)ZS or Zn ozonolysis NaNH2 base NaH base K+ ‘OC(CH3)3 bulky base H2/Pd hydrogenation Hz/Pd/CaCO3 hydrogenation BH3 or 9-BBN then HZOZINaOH hydroboration PBr3 e.g., R—OH -> R-Br SOC]2 e.g., R-OH —> R-Cl 4—CH3CGILSOZC1 (TsCl) tosylate formation CH3SOZC1 (MsCl) mesylate formation ...
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This test prep was uploaded on 04/01/2008 for the course CHEM 215 taught by Professor Koreeda during the Fall '07 term at University of Michigan.

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215 Exam-00-2 - Chemistry 2 1 5 Second Examination February...

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