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chem3a-fall03-final-Pedersen-soln

chem3a-fall03-final-Pedersen-soln - Dr Steven Pedersen U...

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Unformatted text preview: Dr. Steven Pedersen U} luoem Harrie: Siudent’s signature: ~l A‘s name or section number:_ Chemistry 3A Final Exam k7» _______ __ ____-_._.___ M 9robler‘n l _ _____ l? {315' l Problem 2 . ole}- D Problem 3 {Spits} T Problem 4 _ _____ :91 ots E Probler“ 5 _ '21: R Problem 8 _ {24 913) M Problem 7 _ _______ 2.5 sis; Problem 8 _ _____ .35 0‘8. Problem 9 ______ '40 0:5) Total Points No Calculators Allowed Be Sure Your Exam has 20 Pages Be Sure To Try All Parts of a Problem! :35" ' '_ 1?"; ' . - n. 1 . A. Provide one, and only one. rea! exampie for each of thefonowing terms or draw a structure for a given chemical name. (7 p15) a thiol E-2.8-dimethy14-nonen~4-OI C0 (5)4-Ch10TOCYCIOhEXBHB (3 S.4S)-3«methoxy-4«octanol Ix) 2. Predict the product(e) from the following reactions. (20 pts) NeBH,1 ___.._—’... .2 MeOH INN a]! possible stereoisomers (be sure to Show wedges and dashes) H PCC /\/\OH ____* “M0 J No H20 cal—l all expected siereoisorners (be sure to show wedges and dashes) continued on next page Pd/C ““7 ——“—" mrp | only the major product \ 1 . C12, H20 2. NaH Med 3. NaCN 60 or J 5339.54 '- Match the molecules shown below with the statements. (5 pts) . Partly responsible for the Blue in the Blue Ridge Mountains? 5 Grandma said “don’t put green banana’s next to ripe banana's". 22 . A very cool (actually cooling) molecule. C Gypsy moths! I A molecule that tells male bees to “go away. l’m not interested", F Hangover (l drank to much) molecules. 5 and H Absinthe! é Responsible for the miniature flame throwing ability of orange peels. A a F H be; , V a \E/xm ‘ _ I : /\ '_ A isoprene enylena Elmoflene menthol A B D C EigN/ks’sTfleu \ X K o/fi\/\/\ s disulfiram tamer-w hexanoate E F H‘. : i W H thuione acetaldehyde disparlure G H l 5 4. Write logical arrow-pushing mechanisms for the foilowing reactions. (24 pts) | I \\ +HCI—r— / + \ your mechanism must account forthe formation of both products fiflffio @(E) W ‘“ ""7 WA heat Br 4 5( Continued on next page u" ‘—_——’h u 2. H [email protected] H O L a G? “R a“ C15 Lo” J’ \‘l A, £2 0 I,’ 90 E R5 H 0% catalytic HESO4 —r__h OH “.55 H 0/ 9’ Hoéaoe H J. 6‘62” *1 5. Provide the reagents and any other organic compounds necessary to synthesize the indicated product from the starting material shown. For each problem, five boxes are provided in which to place each step of your synthesis. No synthesis will require more than five steps. However, some or all, may require lower than five steps. (20 pts) Br H OH 0-5 3 MozS 4 EéM7bL 5 flgfi 1 IAIN were .54:va Ha“- aim-proud» 2 ?-OG Br 2 A 3 M 51' continued on next page (hint: hydroboration or hydration are not acceptable approaches) . . -- REV-3." dun -. H '-. _.i'5;_ _ _ .‘- . ‘I-QL,‘-« -_— -u'-..' _'_-‘_-;_.—' - -- ' Boron is not Boring! 6. (24 pts) A. Borane does not reduce acetone, but will react with it to form a compound that is in equilibrium with the starting materials. Draw this compound in the box below. acet on e B. Borane. in the presence of sodium methoxide, will reduce acetone. Show the boron containing product resulting from the reaction shown below. Note the reaction is being run in tetrahydrofuran, not methanol. o A + 8H3 + NaOMe ———+ acetone 10 . 'drh“*‘-"‘?f.: ....' Ii.‘ “my. g; .- D. The triol shown below was prepared by oxidizing a compound with the molecular formula. BCme. Show the structure of this compound in the box below. OH H202,eOH OH OH BC‘IOH‘JQ E. In the box below, provide the structure of the triene (a molecule with three aikenes) that led to the boron containing compound in part D. BCH‘JH‘lQ F. When is it best to use Q-BBN instead of 8H3? Place an X to the left of the correct answer. all 2 ' — Q-BBN c When you have mono- and tri-substituted alkenes in the same molecule and you wish to only react at the tri—substituted alkene. )5. When you have mono— and tri-substituted alkenes in the same molecule and you wish to only react at the mono-substituted alkene. a When you want to form a chiral alcohol. _ ' a When you want to form an alkyl bromide from an alcohol. :1 When you want to oxidize a primary alcohol to an aldehyde. 1] w: G. The enantioselective synthesis of alcohols from ACHlFlAL alkenes has been accomplished using appropriate alkyl boranes, RBl—lz. Such boranes are prepared by the addition of a borane to an alkene. This species is then added to an ACHlFlAL alkene, followed by oxidation. - Which alkene below has the potential of leading to an alkyl borane that can then be used in the enantioselectiye synthesis of alcohols from ACHIRAL alkenes? - Rationalize your choice by showing the reagent you would torm by adding borane to the alkene you chose; o and then show the products you would get by adding this alkyl borane to an ACHIRAL alkene. o Explain why this method has the potential for leading to an enantioselective synthesis of alcohols. B C D E F A 5“} ‘\%“‘L . “Q as _.., w grad? Rik 8H2. 4' “J; j/Lfimié + H’Elyz’l A i/ B H diaskaowtefi £"dl47ziose/’(# 53mm 09 a/cm cu pass/'Aé 0512,34 W W64 W we Am“! af/asW/pomuz‘c W . HM" 7%“ “7"?” WWW”; W” W?“ we «4va ,5,“ 5;;mmrM/9 54-94 ,a E AMI/7% W “Md 0 szc int/W % “Natalia 3‘} AM 3, 19 The Basics 7. (25 pts) A. How many neutrons are in ‘30? M B. What does each letter and number in the acronym 8,11 stand for? 5: SUbS'I’HEU‘Hm Minn/mphuk 1:.Unim0/FrU/lr‘ C. Which of the toilowing electrophiles would NOT be suitable in an 8N2 reaction? Circle one. Br Br at M A o D. Draw the structure of a polar aprotic solvent. 5? A E. Show the Newman projection of the most stable conformation of 1,2-dichloroethane looking down the carbon-carbon bond. I4 H H H- o: F. Show the bond—line representation of 1,2—dichloroethane in its ieast stable conformation. rt H 2 NJL a: C0 (3. Draw the major contributing resonance structure of the azide ion: a 9 e) 69 e ' N3 3 N —_— u: azide ion " H. Draw the n-antibonding molecular orbital of ethylene (Le. ethene)‘ H l. The ideal bond angles associated with an SF‘2 hybridized carbon are? /800 13 K. What do the letters in the acronym LUMO stand for? A 11/050151! U: Unod'dffid M:- moktdfa r Ozorbiw L. Show the expected products from the following arrow—pushing mechanism. 041 ME #— U M. Which statement best describes Hammond’s postulate for an endothermic reaction? Place an X to the left of the correct answer. )i The transition state looks more like the product(s) than the starting materialls). :1 There is no transition state for an endothermic reaction. :1 The transition state looks more like the starting material(s) than the product(s). :i Endothermic reactions are always “downhill”. a The transition state is considered “early”. N. A polarimeter is used to: (place an X to the left of the correct answer). :1 Measure the thickness of ice in the Polar regions of our planet. ji— Measure the degree to which a chiral molecule rotates plane-polarized light. a Measure the polarity of a molecule. a Make polarized sun glasses. 5, \ 14 gmanaéaof 8. Grandisol is the major component of grandlure, the sex attractant of the boll weevil. (35 pts) /H lllll’ O ;-\< grandisol A. On the diagram above, label each stereocenter as R or S. B. On the diagram above, circle a Quaternary carbon and label it 4°. C. On the diagram above identity the most polar bond in grandisol and labet it polar. D. How many possible stereoisomers are there of grandisot? E. Dissolving grandisol in acetone would lead to several types of Van der Waais interactions between the two molecules. Clearly draw a dipole-dipole interaction between these two molecules. Indicate your interaction using a dotted line. Your drawing must be specific to receive any points. H 0/ i llll ——~—-+ \< acetone H a dipole—dipole interaction F. Predict the product. H ..../—0’ Hlm\< + Bra —h- G. Write a logical arrow—pushing mechanism for the following reaction. Be sure that your mechanism accounts tor the formation of both products shown. dew H m/ 0 catalytic —.____+ I l I < HZS(D4 H b a a minor product Ho"? '°“ Hui/\ou \\\» f E .0“ ea 0 :5 H. John T. wanted to make the bromo analog of grandisoi shown below. However, aiter reacting grandisol with F‘Br3 he obtained a different compound with the molecular formula, CmeBrz. What is this compound and why did it form? Words are satitactory here. You do not need to write mechanisms! \H/I—fi- H product obtained. CmH1BBr2 desired product CHAD (-3519!an A). 6(- Bap—OH (an an 16 u. .;Né£ural Product Chemistry Naturally 9. (40 pts) A. Scopolamine N-oxide—is a synthetic derivative of scopolamine, a naturally occuring plant alkaloid that has been used as a sedative in surgery as well as a treatment for motion sickness (consult a physician before using”). Circle all of the stereocenters in scopolamine N—oxide shown below. Every wrong circle cancels a right circle. (3 CH3 H scopolamine N-oxide 8. Draw one diastereomer of scopolamine N—oxide. 17 .1il - C. Predict the product. eofgfiHa H20 + NaOH ——"" HO D. Show the product(s) of ozonolysis of abeitic acid. 1. excess 03 -————_—h- 2. excess M823 HO N O abietic acid 18 all possible stereoiscmeric products (show wedges and dashes!) F. One of many compounds isolated from red algae is shown below. Draw the ring flipped conformer of this compound. in the small box indicate which conformer is favored using equilibrium arrows (you do not need a table of data to figure this out). ' equilibrium arrows here ring flipped conformer 19 G. Which word(s) describe the relationship between the bromine and chlorine atoms in the cyclohexane ring of the compound shown below. Place an X to the left of every answer that is correct. Every wrong answer cancels a right answer. compound from red algae o cis o diastereomeric i. trans o enantiomeric o syn 1:1 eclipsed pr. staggered 7L diequatorial H. Predict the product. 61’ Table of select pKa’s K3 CHchaH I mmummuumHumImnmnwu‘u HIIHIHIIHIL l Illlllll-Illlltl 2 HI |l|||IIIIIIIHILIIIIIIHHH HAYDEN [IE] :W-IV'EIL Slicntrr unuucn GWMW — SYMHOL -— Aromc NquER ATOMIC WEICHI THE PERIODIC TABLE nut-1! "".-‘7-uf.' +—.'—._ . I1 17'31 III III III" WM 1911 IN] llll Itll IHI fill I51 I‘M IN. TRELE 1-2 ifiemi'fi'éqatgfitigS'u! Selected Elaments A.“ Nauflr‘ahnmhfishudby LPmlingIndupduedhyA. LAllred(se¢ ernafaflnargmicandNnctearChm- 1m): 1961. I7. 215). ‘ ' " . ._ wlhnilflis‘miafianherniasrfnL-Snm filkanes a! M" ' ' ‘etfi. - -"' . I": '- _ .- - I -— (CflghCI-H—CH; I 83 - (came-yen; 87 (mahcnmmm): 855 (m3hC-E-CtCHJ): 73-5 "(cgahCHCHz'i'i-fi ' (cughcm-HI. _ - _ (Grimm-H _ ._ .96-5 ..- N032: Sac W for m. 3-1. ...
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