Spring 07 Exam 3 Blank - CHEMISTRY 225 (12) (25) (09)...

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Unformatted text preview: CHEMISTRY 225 (12) (25) (09) (1’3) (75) TEST #3 1. JUNE 1, 2007 2. (13) NAME 3. G O 0 D L U C K ! 4. USE MODELS!!! 5. Atnmie numbers: H=1,C = 6,N= 7, O: 8,, S = 16, (31:17, Br= 35 TOTAL 1. (l2 Paints) CHIRAL MOLECULES. a. ( f 6) Cnnsider the list nf erganie mnleeules belnw. Cirele all chiral mnleenles;' underline all aehira! meleenles. I H3C CH3 / \ CH3 t t t , ' “a... .--OCH F E 0—0 N 3 CHECHECHEIIZ=CHCH3 eH3 b.( Drg. Left. 211W, 9, 1351 Butyleyeinheptylpreniginsin .w’ 6) The highly fnnetienalized meleenle belew has been identified as a key intermediate in the tetal synthesis ef spirangien A. a structurally eemplex antibietie iselated frem Serngnfnm eeflnlnsnm. The synthesis ef a pertien nf this melee-tile has been aehieved reeentljr by ehernists in Germany [Tennhedrnn Lea". 2007, 48. 2905]. ea OH 9H CH3 6H3 CH3 i’ l 6H CH3 6H3 6H3 Ml “a I (3) .Direetly en the stmetnral fermnla, label all sterengenie earbens with asterisks. I ( 1] Determine the tetal number ef aannrinmers ef this enmpeund. 2 l (2) Disragardiag canfigarafiaa at that dnabfa bands: dctcrminc thc total numbct 0f diastarcamcrs cf this ccmpaund. Yuan may lcaac yam answcr in cnpcncntial farm. 2. (13 Paints) STEREOCHEMISTRY IN ORGANIC REACTIONS. a. ( f 3) Thc fallcwing ccnvcrsicrn using a chiral catalyst was dcvclapcd rcccntly by chcmists in Japan [Tctrahadraa Left. 2007,, 48, 2939]. It pmduccs a singlc stcrcciscmcr in high chanticmcric purity. chlral OH _" catalyst l QCHO + {CH30H2}22FI —l'" CHECHE H {Hystaraciscmar I (3) Writc a stcrccchcmical fcn'nula far thc (Bystctccisamcr that shaws its absclutc ccnfiguraticn clearly. Yau may asc thc symhcl Ph (fat phcnyl) ta rcprascm thc aromatic ring. I (3) BONUS QUESTION! A dii‘fcrcnt rcscarch grcup in Japan dcvclcpcd a'raiat'cd-rcacticn far thc - prcparaticn cf substitutcd cyclchcaancncs [Tatrahadraa Lari. 2007. 48, 3093].: Undcrccrtain.‘ ' ccnditicns thc cyclchcxancnc dcrivativc was fcrmcd in high cnanticmcric p-ar.itai‘=uan-caamnlcis-. - shcwn hclcw. Dctcrminc thc ahsclutc ccnfiguraticn cf the cyclic prcduct.- O O a chiral lL catalyst f”: + (CHsCHslzzn —"' b ans. "'CHECHg h. ( I 4) Chcmists at the Univcrsity cf Scuth Dakcta havc dcvclcpcd a “gt-can” mathccl fcr thc caidaticn cf arcmatic ccmpcunds tc alcchcls [Tarrahadma Left. 200?, 4’8. 341?]. An caamplc cf thc stratcgy is shcwn bclcw. Dcscrihc thc starccchamicaf aarcama cf this rcacticn and bricfly justify yam“ answcr. OH ' L air. ta hita — l QCHECHS _-_Q_ll_+ Golan—[3 (and atharpraciucts} a J c. ( f "D As we will see later an in the cnurse. terminal alkynes can he ccnserted tn cfahalkenes by a set cf sequential reacticns. The precess is depicted in generic fcrm belcw. RH fCHg Ft—CECH ——-J-— R—CEC—CH3 —:- 9:9 H H I (it) Suppcse this same set cf reacticns were used fur the synthesis cf (R)-C1FS-4-m3th}’ln2- hexene. Deduce the structures cf the terminal alkyne reactant and internal alkyne intermediate that weuld prcduce an enenticmertcntiy pure alkene prcduct. —_ ' CH3 ' __fi a... \JVLH H {R} -cie—4-rnethyl~2rheaene I (3} Ccnsider the trens-iscmer tn the right. Determine the a - . .. ' rstjerecchemical relatinnship between the trans-iscmer and (R)-cis-4- . - c H3 a . ? | ' methyl-2-heaene. Circle at! that apply. ' '_ Structural ishmers Sterecisnmers Diasterenmcr's I Enanficmers Retatinnal iscmers d1 ( f 4) Chemists in India have recently ccmpleted the tntal synthesis cf the anti'-' tubercular agent emgcrgiaene [Tetrahedrnn Lett. 2007. 48, 2841]. I (3) The first step in the synthesis was a catalytic hydrcgenaticn cf an unsaturated ester (equaticn helcw). Write the structure cf the prcduct cf this reacticn with due attenticn tc sterecchemistry. H30 "I! i H2, catalyst MCOECHE, ill—lg i . . . : H38 I {1) The chiral aldehyde tn the right was prcduced in a View 0 subsequent step in this svnthctic sequence. Which term [a l g i .J F I I H accurater describes the sterecchemrcal relaticnship between 3 H this ccmpcund and the ertginef unsaturated ester (circle cne)? CH3 Same relative ccnfiguratiun Oppcsite ccnfiguraticn Inverted ccnfiguratinn 4 3. (26 Paints) STEREOCHEMICAL FORMULAS. L-Serine, structure belcw, was used as a chiral starting material in a recent synthesis cf ccmpctmds related tc the binlcgically active mclecule shikimic acid [Tetrahedron Lett. 2007, 48, 3512]. a. ( I 18) Using the templates presided: ccmplete the sterecchemical fcnnulas fcr Ln serine and its enanticmer D-serine. l COEH \k J Hrs/\r" c—CHEOH NH; "l L-serine D-serine b. ( r’ 3) The sclubility cf L-serine is 5.0 g per 100 ml cf water. Estimate the scliibility cf D-serine in water. Briefly justify ycur predicticnq _ c. ( f 5) I {'3} Determine the absclute ccnfigtn‘aticns cf L—serine. and D-serinc I (I) The specific rctaticn, [ctbg fer L-serine is 45.8”. Is L—serine dcatrcrctatcw cr levcrctatcn’ (circle cne)? I (1) What abcut its enanticmer, D-serine‘? (Circle cne) deatrcrctatcrv levcrctatcry Impassihle tn determine frcm the infcrmaticn given 4. (09 Peints) STILL MORE STEREOCHEMISTRYI a. ( r’ 4) Write structural fermuias fer a chiral? and an ashtre! seeendary alkyl bremide each with the melecular tbrmula CTngBr. chiral RX achiral RX b. ( r” 5) 3.4—Dimethylhesane (Test #2) has twe stereegenic carbens and can esist in three stereeisemeric ferms. I (3) Using the sawherse framewerk belew, 1arrite a stereechemical fermula fer the eehtrei stereeisemer ef 3,4-dimethylheaane. HINT: there‘s a plane ef symmetry and the stereegenic carbens have been shewn. I (2) Using an}; apprepriate stereechemical fermula. write a structure fer a chiral structure! isemer ef 3.4-dimethylhexane \ / / aehiral 3,4-dimethylhessee -|_n_n_na chiral structural isemer 5. (10 Peints) MULTIPLE CHOICE. Write the letter ef the mest cerrect respense in the space presided te the left ef the questien. The cenuersien te the right was utilized by Chinese chemists in the ceurse ef a synthesis ef certain cyclic sugars [T‘etrehee’ren Lett. 2007,, 48.. 3093]. What term best describes the stereeehemical eutceme at the rseetien site? A. Retentien B. Inversien C. Racemiaatien D. lmpessible te determine Which statement is always true? A. All diastereemers are stereeisemeric. B. All stereeisemers are enantiemeric. C. All diastereemers are geemetric isemers. D. All stereeisemers are structural isemers. the right? 6 Whieh strueture belew eerreepende te the eneerfemer ef the mine eeid te [EH3 H2N\ H PM? (I3H3 H. 't .C '- -—ee H C “pea HzN‘ 1E002H {C 2 H36”; H‘u‘;3(32|-| H / COEH A. H 3. H30 0. e. H2N The Speeifie retatien ([eflg) ef (R)-3-hexenel is 53.2“. A sample ef 3—hexenel frem the eteekreem was feund te have retatien ef 4“ under the same eenditiene. Determine the stereeisemerie eempeeitien ef this sample. A. Enentiemerieafly pure (BS-hexane] B. Enentiemerie exeees ef (R)-3-hexenel C. Enentiemerie exeeee ef (S)-3—hexenel D. Enefltiemerieally pure (SJ-hexane! Whieh greup weuld be fleeigned the highee! prierity by the Cahn-Ingeld—Preleg system? A. -CHECI H. —CH0 C. —CO;H D. —C(CH3)3 ...
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Spring 07 Exam 3 Blank - CHEMISTRY 225 (12) (25) (09)...

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