225Sp09 Test 6 Key - CHEMISTRY 225 TEST#6 1(33 2(18 NAME m 5 w e v iC—t 3(14 4 —(10 TOTAL(75 G 0 0 D L U C K I I(24 Points ORGANIC REACTIONS a

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Unformatted text preview: CHEMISTRY 225 TEST #6 JUNE 26, 2009 1. (33) _ 2. (18) NAME m 5 w e v iC—t- 3. (14) 4. — (10) TOTAL (75) G 0 0 D L U C K I I. (24 Points) ORGANIC REACTIONS. a. ( / 24) Complete SIX of the following organic reactions with structures for the reactant, product, or reagent as required. Pay due attention to stereochemisrry and regiochemistry in those cases where such characteristics are important. If no reaction is expected under the reaction conditions, write “NR.” and explain briefly why the reaction fails. If you complete more than six reactions, please be sure to indicate clearly which six you wish to have graded. Each problem carries equal point value. Cl C —OOH $13 0 I OH Tetrahedron Lett. 2009. 50, 3517 Note: T5 = toluenesulfonyl, unaffected by reaction ( + enantiomer) OCH20H3 1' OS'JBO H 00:0 (EH3 3 + 2. (wake; CH30HCHO HBr(g) (EH3 Bf —/ "‘"’—" (only product) b. ( / 9) Write equations, including reactant, product, and reagent to illustrate each of the following reaction types. 0 An E1 reaction to produce a cycloajkene. /~i/ew Lmr /“ ,_. , \L—j\‘mg C41; 6%. 01> 61+ L” MEL”; 0 A syn addition to trans-alkene Us; H ' MV/ " /\f__/ 0 A Markovnikov addition to a terminal alkene a, M . H {4% D'“—““* /\/L\ 2. (18 Points) REACTION MECHANISMS AND INTERMEDIATES. a. ( / 5) Write a detailed, stepwise reaction mechanism to account for the following transformation. A complete reaction mechanism will include structures for all intermediates and curved mechanistic arrows to show the “flow” of an electron pair. N f ©0l—h—CH2 CHBQH. H“ O<OCH3 ~ 34‘} i l CHZCH3 i HQ e/>\# mi U7]; m; or we» H b. ( / 6) Ethoxide anion and acetate anion are both oxygen-based nucleophiles, yet when they react with a typical secondary alkyl halide they yield very different products. e CH30H20 0 1| 9 CHac—O - Z 5N I (4) Complete each of the two reactions with a structure for the major product. 0 (2) Account briefly for the difference in reactivity between these two reagents. EWx:gla ‘WV it, cs 9Jv0- Large: ('4; W “said \[CAiy-g’, .a‘i’ificruei) aut‘i gt Qfl-vvhxaé'é- olvui EL Veercinrou a Lit—CM ea» Le\\(‘\f- “5‘9 a. pub-‘FL weciLx_-v Lace) Lufut'irc, o Few-(«Lui- vxwiesffléh v View/sieve, "Vi veeri} a 4e..mwla7 Wixri’f. L7 a... 9N2 FGTLbUas7~ J I c. ( t 7) Write structures for: O (2) the trialkylborane I (3) the transition state for the o (2) the bromoniurn formed from 1-butene E2 reaction of 3-brornohexane ion formed from to produce cis-3 -hexene cyclohexene trialkyiborane bromonium ion 3. (14 Points) LATE-BREAKING NEWS FROM THE WORLD OF ORGANIC CHEMISTRY. a. ( /3) o (3) Dimethyl fumarate, structure below, was named Molecule of the Week for the week of June 1, 2009. Complete the catalytic deuteration reaction of dimethyl fumarate With due attention to stereochemistry. CH3OZC\ ll oz, PdiC 53:9 —«3t H H3 dimethyl fumarate catalytic hydrogenation ester hydrolysis 0 (2) BONUS QUESTION! Catalytic hydrogenation of dimethyl fumarate followed by hydolysis of the two ester groups produces succinic acid, Molecule of the Week for March 31, 2009. Write a structure for succinic acid. H132. C OLE C/Lk succinic acid 5 b. ( / 3) As is frequently the case in organic chemistry, a particular compound can be prepared by several different methods. For example, compound A below was recently synthesized Via a Smlg catalyzed cyclization reaction by British chemists [Tetrahedron Lett. 2009, 50, 3185]. Suggest an alternate route to compound A by a dihydroxylation reaction. Include the structure of the reactant and the reagent(s). O H or: r o : Sml2 CH3 E / \ W THF, MeOH - 5 CH3 s 0 compound A compound A z c. ( / 8) Organic redo}: reactions. 0 (2) The following transformation was reported by chemists in Germany [Tetrahedron Lett. 2009, 5 0, 3184]. For carbons a and b identify whether there has been an oxidation, a reduction, or neither (circle one). 0 OH 3 0H several steps a b0C H3 I) OH 0 At Ca oxidation neither oxidation nor reduction At Cb @ reduction neither oxidation nor reduction 0 (3) The following reaction sequence was utilized in the course of a total synthesis of the four stereoisomers of (l ’S)—1-ethyl—2-methyipropyl-3,l3-dimethylpentadecanoate, the major component of the sex pheromone ofPaulownia bagworm, Clania vairegata [Tetrahedron Lett. 2009, 50, 3266]. ~Write a structure for the initial reactant in this sequence. - BONUS QUESTION! Complete the three-step synthesis with a structure for the final product. NOTE: in the original paper a chiral reducing agent was used to form an enantiomerically pure alcohol. 6 O (3) There is a very timely article in the June 22, 2009 issue of Chemical & Engineering News concerning the possibility that ozone is formed in the human body. According to the article chemists at Scripps Research Institute are using cholesterol as a probe for the presence of ozone. Complete the reaction on the following page with a structure for the ozonolysis product of cholesterol. 4. (10 Points) MULTIPLE CHOICE. Not the usual collection of word problems. There is but one correct answer for each question. 0 Circle the reagent that converts a primary alkyl halide to a terminal alkene; underline the reagent that converts an alkene to a 1,2-diol. NaBH4 H' KMnO4, OH'(aq) - Circle an intermediate in the acid-catalyzed hydration of 1-butene; underline an intermediate in hydroboration of 1-butene. 69 CHgCHgCHgCHzBHz CH3CH2CH2CH20H2 CH3CH2CHCH3 6—;— BH2 0 Circle the most stable carbocation; underline the carbocation most likely to rearrange by an alkyl shift CH3 '7 9 e eel o CHCH3 H 0 Circle the electrophilic reagent; underline the reducing agent Br' NaBHi. "OH/H20 0 Circle the major product of acid-catalyzed dimerization of 2-methy1pr0pene; underline the prod ,. " 'u' ion of bromine to cyclohexene in water. M UBT [ i Br "'Br ""OH ...
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This note was uploaded on 06/18/2010 for the course CHEM 225 taught by Professor Markdec during the Spring '10 term at University of Michigan-Dearborn.

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225Sp09 Test 6 Key - CHEMISTRY 225 TEST#6 1(33 2(18 NAME m 5 w e v iC—t 3(14 4 —(10 TOTAL(75 G 0 0 D L U C K I I(24 Points ORGANIC REACTIONS a

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