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PROB. SET #3 - CEM 352 Spring 2009 Third Problem Set...

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Unformatted text preview: CEM 352 - Spring 2009 Third Problem Set Chapters 21E 28: 29 - Chapter 21 Review Questions - Name the configuration (R or S) at each chiral center of the following aldose and draw it in Fischer projection. CIDHZO H a) Draw the a + it furanose forms of the C——-O following sugar in Haworth projection: H H H H H H20 H b) Draw the a + [3 pyranose forms of the following sugar in Haworth projection: Enc'ircle the single sugar which does not mutarotate when dissolved in pure water: H o H H o 0 H C H20 0 H20 H 3) KT—l l—l>i 0/1—1 ‘ - C H30 0 —E H C H3 0 H HZOH H20 H H ‘ Al) Complete the following Haworth projections for the following 2 sugars: C H O C H20 H H O H H H 0 -—IP H H H H H .H20 H g—pyranosa a-furanose 9 In the more stable chair form of the following pyranose, how many of the fivesubstituents will be in' an equatorial position? CHZOH -——O O H H answer e), (4 pie). 9 The partial structure of sugar X is shown below together with several observations. Deduce the complete Fischer projection formula ofX: HNO 0 Ho /—3> An optically active aldaric acid (diacid) éHOH cm H H i, 2 aldohexoses, both of which 'are, H20 H sequence oxidized by HNO3 to optically active aldaric acids x H o H H C H20 H x Complete the Fischer projection of sugar Y (Y has a differentmelting point from Z). ( ) 4M& CHO CHO CHgOH ' ' HZOH _4- The following observation was made for aldose A, whose partial structure is given below. Deduce the complete structure of sugar A: C H O C H O H Killiani- C + D HOH gigteernce J HN03 J HN03 H H optically optically ”20.“ fl” 3%? Hon A - Sugar A (answer) The following observation was made on aldopentose B. Deduce the complete structure of sugars B, X and Y. C H 0 H H Killiani- Q d“ CHOH -j~—-_—> Sugarx and Sugar Y B e'W't 6*} H H ESSELCQ flood to 4k a rd 03 +0 WWW“; H20H a-PH uni/L1 0.0% M13. cv\-:‘-‘1—‘3*&’Q 3 Sugar X is oxidized with HN03 to the same diacid as Sugar Z(Z is not identical to X) CHO H H H H20H H20H CHZOH B fix i (a Dcduoe the structure of (+)Whonose, (-)Younose, (+)Inose and (~)Godnose from the following o bservations: ‘ . . mixture of KFF mixture of K4: , 2sugars > 45ugars 1) D-glyceraidehyde mixture of 8 sugars, one K'F of which is (+)Whonose 2) (+)lnose K'_F> (+)Whonose + (-)Younose HNO 3) (+)inose 3 >— an opticallyinactive diacid . HN _ 4) (+)Whonose —03> anopticaily active diacid HNO ) (-)Y0UH'OSB 3 > an optically active diacid 5) (+.)Wh0nose fl, same diacid £303.. (')GOdn05€ Cha ter 21 Review Questions Problems from Textbook Chapter 21 1—4, 8, 14, 22, 23, 26 Chapter 28 Review Questions Problems from Textbook Chapter 28 1-10, 13‘19, 24—28 Oi - Chapter 29 Review Questions - 1' flu 0- at? H CH3 CH3 H H CH3 H ‘ E,Z,E 222 E12 The above trienes can undergo electrocyclic ring closure to give one or more of the following cyclic dienes: : CH3 0;; : CH3 T > < T c; H H CH3 CH3 H H cis trans trans 1. For a thermal process: a) Draw an arrow mechanism for the formation of product. b) How many electron pairs are involved in the transition state? c) Is the HOMO of the transition state symmetic or asymmetric? d) Is the conversion conrotatory or disrotatory? 6) Give the diene product(s) from each triene. 2. Repeat question 1 for a photochemical process. II. For each of the following cycloaddition reactions: 1) 2) 3) 4) 5) SJ b) O V Draw an arrow mechanism for the formation of product. Give the values for n and m for each (n+m) cycloaddition. Give the symmetry of the appropriate HOMO and LUMO for each reaction. Is the observed reaction antarafacial or suprafacial? Will reaction occur A or hU ? 002a | / N on / \ + (CN)2C=C(CN)2 —> ON A CN N CN \ O _, m 0 Q + o ———» / O_Q + (CN)ZC=C(CN)2 l COgEt III. la. Name the kind of sigmatropic rearrangement that occurs in each of the following reactions: . Usrng arrows. show the electron rearrangement that takes place in each of the reac- lions. \ m A H CH3 CH3 CH2 CH3 CH2 CH3 0) .2q \ CH3 CH2 CH3 Which is the product of the following [1.3] sigmatropic rearrangement, A or B? 0 ll 0 H 054 . D CH3 (II) A occnJ OCCH3 -—a / H H H D D H A B Chapter 29 {Two products are formed in the following [1.7] sigmatropic rearrangement. one due to hydrogen migration and the other to deuterium migration. Show the configuration of the products by replacing A and B with the appropriate subsfiments (H or D). Chapter 29 - Review Questions Problems from Textbook 1-6, 8, 17, 23, 24 ...
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