W08%2c%20140B%20FINAL%20EXAM%20KEY

W08%2c%20140B%20FINAL%20EXAM%20KEY - To pick up your graded...

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Unformatted text preview: To pick up your graded exam from a box outside 5100A Pacific Hall sign here: mammv r403 NAME (please print) FINAL emu FIRST LAST Mme” 20. 2003 SIGNATURE ID NUMBER WNAME OF PERSON SEATED IN FRONT OF YOU: MSTNAME OF PERSON $543150 BEHLVD YOU: DO NOT OPEN THE EXAM UNTIL YOU ARE TOLD TO DO SO. — Please sign your name on the top 0! each page. — Please check to see that you have 11 pages (including this one). The one blank page may be used for scratch work. but DONOT use mescraMpage foranswers. Answer in the space provided. Do not write answers on the back of a page. Question Points Sacra l 42 2. 48 3. 40 4. 50 5. 20 Total 200 H He LiBe B c N 0 F Ne NaMg AlSiPSClAr KCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKr RbSrY ZrNbMoTcRuRthAngInaneI CaBaLaHfTaW ReOsIrPtAqu'I‘l NAME: la. (8 par) Triphenylphosphine can be used to cortvert epoxides into alkenes as shown below for the A to B conversion. Write a detailed mechanism for this transformation. Used curved arrow notation to show the movement of electrons. Be sure to show the structures of all intermediates. Recall that PPh3 undergoes reaction with alkyl halides in the preparation of Wittig reagents. 0‘7 / Phu--}CA""MH \ + IPPha—r PhCH=CHPh IF 41-1 (“MI/£3! «ht-(aw; mu («flew-a 1b. (8 prs) Shown below is a reaction in which furan C undergoes reaction with alkyne D to give furan E and alkyne F. This reaction is related to chemistry that you encountered when we discussed the reactions of conjugated dienes. Write a detailed mechanism for this transfonnation. That is. use curved arrow notation to show the movement of electrons. Be sure to show all intermediates. / A M6020 + M60020 2 002m —»- D + TMS«-——_-—TMS ““I-n. TM 0 M902 F c TMS=SIM53 M 0 ‘%° 1"” ' ' p62 c/xf‘W—v flw—e F ’L F r'} \JI // (Ev-Mu ml) ‘W‘O 5 I‘ll NAME: 1c. (I0 prs) Circle each of the compounds shown below which are aromatic and place a box around any compounds that are not aromatic. ASSUI’fle all structures are planar: Id. (16 prs) In the four sets of compounds shown be10w. circle the thermodynamically more stable isomer of each pair. cis-cycloocten : 0H cis-S-hexene trans-cyclooctene NAME: 24!. (25mllnthcboxcspluvidemmwmcmofflzesmdngmmlnwdformhohh: foliawingtnnsfm-nnfions. Show meochemistry where appropriate. 8] Pr ang) D HCI, A OMe CF3603H O o 5* melmbeaocfi f‘ .9 2b. 2:. NAME: (I5 pm) For each pair of intennediates circle the one that is more stable. f’""“‘"- (8 pm) Give the structure of an alkene whi and subsqu OR 63 on “ CH2 0F! H36 ® Br H Br H H °" 0 OMG NAME: _. _ 311. (I4 Pts) Virtually all vitamin C sold is synthetic material. At an early stage in the synthesis, the net be selectivley oxidized to a carboxylic acid primary alcohol group at C1 of the Sugar sorbose m ns 3 through 6. Sorbose exists mostly as a function. without affecting the OH groups at carbo c clic hemiacetal. Upon acid—catalyzed reaction of sorbose with excess propanone Y [Cl-[,C(=O)CH3), compound G (shown below) is formed. Deprotection of G with aqueous acid Draw the structure of sorbose in both its cyclic hemiacetal and its acyclic form. gives back sorbose. Correctly indicate relative stereochemistry for the cyclic form only. H CH O O 3 H OX r \ CH3 H+ o CHaOH ‘—"' SORBOSE O H exess nae/V G H20 "tel-gall H H 0‘“ at! 49.23 “+1510”? Yea: acfiltqugnoog 25%;: sorbose in its cyclic hemicacetal form 3b. (6 Prs)_ Glue the strucmre of two compounds. One that will exhibit both 11: to 11* and n to 11* transitions in the UV~Vis specuum; and one that will exhibit a longer it to :rt“ transition than the first structure that you give. NAME; Sc. (20 prs) In the boxes provided, give the reagent(s) needed for each of the following transformations. More than one set of reagents may be necessary for a given nansfonnation. a) 0 Hz U M {a 0/0 b; 9 mac? CHSOi—Q—Me —--—-—~ CHsocHs CMS c) d) e) NAME: 4. [50 pr} Predict the major product(s) for each of the following reactions. Write "NO mellow where appropriate. Show stereochcmistry where appropriate. Assume an chiral starting compomds are optically pure. For any product that exists as a raccmic mixture write “racemic” under your product mm. a) 2. 2n, MeCOzH b) 0 Me _Br_2.. FeBr3 C) d) \/\\\rpr MeBr f) 9) h) I) O A (IOH OH 0H9 heat and removal of water as it forms H+ 0 2K NaBH4 EtOH 0H9 I ._ heat and removal of water to shift equil. to the right 1) MeLi 2) w, H20 5a. NAME: (20pm) Formhofihefollowingonestepmnsfomnfitmsshowflnmmof electronsbyusingdaemndudcurvedmownouflm Showallfu'unlchmgesfonach mmflwkfimflfiginofflnmcfionarm. 8) o_p 4m pm w _—~——- it w ,9: b) d 0 rm 4. Eifihg -——~—— {I V“ Et H C) _ “cognac - -' HO: —___-.\"‘H 4. m "WE-110» C // M blot,“ d) D Her-3 4111 .091? ’11 H CHadH a” 7L " 0H 0) OH H Q“ “OH H XH m Qt}? HO a H 1:! OH H ,1. OH -/ H 10 ...
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This note was uploaded on 08/05/2009 for the course CHEM 140B taught by Professor Nefzi during the Summer '06 term at UCSD.

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W08%2c%20140B%20FINAL%20EXAM%20KEY - To pick up your graded...

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