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30C_2008W_Final_Key

30C_2008W_Final_Key - Chem SOC Winter 2008 Final Exam Prof...

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Unformatted text preview: Chem SOC, Winter 2008 Final Exam Prof. Ohyun Kwon, UCLA Your Name (Please Print) ' Wfiiiestim ' Youf'pamt‘s' " ""2'(§p¢in'ts)' '3 " 9 \ 1(16p01nts) / 3 "(8 points) 9 ' 4(12' pdints)’ ' 5 (22 points) 1 Z 7( points) I g a (9 ; ””“11'(‘1‘§fibfiifits)’ _ . “i“2”(13paint's”i ,. , __ , E A'1'3'(”19”;56~i}if§3' W V Tbtalkibbfibihifi 3 ' - " ; s l g l l l l l, E i z i f i l i E E E i E i E % § E E E l § 2' t, I , N \ g (:j’ /9/v—uMahflannmc Chem 30C Final, Page 1 1. (a) (6 points) Write a Fisher projection of D-mannose, a Haworth projection of a-D—mannose and a chair conformation of a-D-mannose. (Mo layuck E E i ; H0 [1 E l i D-mannose i a-D-mannose a—D-mannose 5 (b) (10 points) Name the following molecules. NWZW;;;L§ W, ., mm, .m , Em m (. W. A ,. M, ., .... ,.. , ., w W MM, “M“..-l WWW...“ NW WWW c ‘E O i i E MN Br_ i Jgfm’khuwkmmonmrn L'lrvm'JL (TEA-B) g l 9 § : i Cl 51 Emu ulml’ § 2 | Cl [MW WU g l- lot/W» ---—L|r -——Llnlwo 7.- Wéolnn'zcne Chem 30C Final, Page 2 2. (9 points) All attempts to synthesize cyclopentadienone yield only a Diels—Alder adduct. On the other hand, cycloheptatrienone has been prepared by several methods and is stable. Draw a structural formula for the Diels-Alder adduct formed from two cyclopentadienones (specify relative stereochemistry). And explain what accounts for the marked difference in stability of these ketones. a A “TY (Whufino lESonqme Sin/[WK 'EDI' (\iDloP-enhutlfi‘mf l’lfiLS U‘fil) fiat?- ’Uelmm)( wth— arnmfllfi) llflUC'ch. athehcl) unShMe 2— ham ”RH-m «Eu (5 3 a On ‘4’an Mu haul 0* W3“ mmluhhb momnte Swan {yr (lwhelh‘fiw‘e in” m‘ 1‘ clean“; LWMW ') Hamlwt veg 5111th RC \qblj unrtmuwe (bed: 3 Chem 30C Final, Page 3 3. (8 points) Histamine, an important chemical in our bodies, functions as a neurotransmitter and a potent vasodilator. It is the agent that causes many symptoms of the common cold (hence antihistamine drugs being sold over the counter). Rank the basicity of each nitrogen in histamine and explain why. 7_.. ® lama \WW Worms on w, “W '3 Srl’lfljhn'tliucl Wore-hrs , \st \"Mu c tn Wan, @ m“ pi." {\tmg ram/sq “M39“ n a. {Awe-(L I hWMkh‘L U11 {\5W\\ 5W MA W mulabk {V 1. WWW Chem 30C Final, Page 4 4. (a) (3 points) Propose a structural formula for compound A, CloHlé, and account for its formation. '2' 7 1. 2 equiv Mel .2 H 2. H202 7 .- I. NH2 3. heat ‘14 SQ a H (b) (9 points) The value of Hofmann elimination for the determination of amine structures was first illustrated by the following series of experiments. Based on the results shown below. 1. Mel (excess), K2003 1. Mel (excess), K2C03 C5H11 N C7H15N M . _ , 2. A920, H20 2. A920, H20 p|pendlne 3. heat B 3. heat 1’4-pentadiene 1. Draw the structure of compound B. B ii. Propose two additional structures (with molecular formula C5H11N) that are also consistent with the results above. at. Chem 30C Final, Page 5 5. (22 points) Provide structures of the products or reaction conditions. (a) © conditionA HzNNHz-KOH ? "(L (b) 1. conditionB 2. H20, heat condition 8 NERO” “(A HOQBr 6. Propose a synthesis for the following transformations. (a) ( points) Chem SOC Final, Page 6 Chem 30C Final, Page 7 7. Propose a synthesis for the following molecules using the given starting materials. (a) (12 P011118) antihistamine histapyrrodine- (9 Chem 30C Final, Page 8 8. ( points) Chlorination of ethylbenzene under radical reaction conditions is less regioselective than bromination as shown below. Explain why by applying a postulate proposed in 1955 by George Hammond and by drawing energy diagrams for relevant reactions. Heats of Reaction for Hydrogen Abstraction in Ethyl Benzene Reactlon Step AH° (kcal/mol) @CNIBS (PhC02)2 + H—Br CCI4 + B: —-> heatorlight —2_+©):\: ©/\/CI g: + Br +©/\ + H—Br + Cl +©/\ + H—Cl m Kw imam m] 810? m 11.5qu “W“ . R Phi. “MWUH’A' a. la Abra 91 a Man)» Ker wwfinfinhdt U) “(k We “was “-4 [Whal’fibflh chMhs-n. t2 Camlacrnfg‘r m4 Ml— (Ml‘nm‘lfl. lmmlhm i3 eulorhcrml kW "Cum” 7'— 2, U) Hui-um: WHER- wM-Hrw Wan-m Shy-K ‘evaw fishermn, $1.12 ......____.__..___.________=_=_____fi . lamb} “M “1! W ”l M r M oak-1m...“ m Paar-Mel lav-Lb, u—_.__.___..——--"'H ' RH‘U ‘L .9) Hawk“ “at. T 31 id‘: 5r- CNMMM bah-e». VH1; butrlq cklonhmwx “‘33 hamljlu GMth-mm l) o\ [if Mull" Hun ‘ml' 1»- Dig-3W —"5 Thaf‘} “”7 Mini“). “9""an WM 2‘ gal milW‘Jl thuvIltlnillhlle chlmm t R Chem 30C Final, Page 9 9. (a) (8 points) Predict the structures of the expected kinetic and thermodynamic products from addition of one mole of HBr to the following dienes. Kinetic product Thermodynamic product M Kinetic product Thermodynamic product (b) (8 points) Provide structures of the following nucleophilic aromatic substitution and briefly explain why the reaction provides two products instead of one (simple substitution product). Nefi,‘ “r WA] 1,: 81 “\L Hm VTK Wm‘chfl “a Chem 30C Final, Page 10 10. (12 points) Predict the structures of the products of the reactions shown below. Specify the relative stereochemistry of the chiral centers in the products if there is more than one chiral center. (a) Use of Lewis acid (EtQAlCl) improves the endo selectivity. Et2AICI OMe CH2C|2, 23 °c (c) CO Me / O 2 heat \ O + II 002 COzMe (d) U + H2N I \ Pd(OAc)2 B(OH)2 N / Br N32C03 , Chem 30C Final, Page 1 l 11. (15 points) Show the products of the reactions shown below. (n) Pd(0Ac)2 Ph W + PhBr + W PPh3 EtaN fv PH (b) (e) 000' 6 JL chorismate mutase ; o 000— 6H (d) CI “30y" OTBS I'Rua 0TB) CI’ IIDC Ph Wows V3 (”35 W0 CHZCIZ (0.005 M) OBn 012..., 7) TBS = t-buty|dimethylsily| Chem SOC Final, Page 12 12. (a) (9 points) Which of the compounds below are expected to be UV/Vis active and which are not? Briefly explain why. Chem 30C Final, Page 13 13. (19 points) There exist similarities between the mechanism of nitrous deamination of 2- aminoalcohols and the pinacol rearrangement of 1,2-diols as shown below. However, the first reaction gives ring expansion, but not the second. (a) S ow thmlianism of each rearrangement. ,, f- H # n q {—34 ‘ we ’ " a . “£31,, jl ...
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