225Sp07 FR Key - CHEMISTRY 225 FINAL EXAM PART I(FREE...

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Unformatted text preview: CHEMISTRY 225 FINAL EXAM, PART I (FREE RESPONSE QUESTIONS) JUNE 27, 2007 NAME A mgwtxx Lain? __fl GOOD LUCK! Part1 ZO’SQ?) M.C. 3 I ,S right @ 2pts each = CO 3 (98) TOTAL 8; ' ‘5 (125) COURSE TOTAL (500) EXTRA CREDIT QUIZ (20) COURSE GRADE (27 Points) Answer each of the following questions. The point value of each question is indicated. a. (2) Write a Newman projection for b. (4) The compound below is a component of the 2-methylbutane in which there are two mating pheromone of the agricultural pest sets of gauche methyl groups. Phytophthora. It has recently been synthesized by Korean chemists [TetrahedronLerL 2007, 48, 4601]. 0 Convert this structure to a jagged line formula. 0 Label all stereogenic carbons with asterisks 0 Show how this compound is made up of four isoprene units ‘\\§ Ubfgg ‘3”3 ‘st ‘13”3 ‘FH3 HocH2cH(CH2)3<|:(CH2)3CHCHZCH2£H:C HCHzc H20H OH 0 Newman projection jagged line formula c. (5) A stereoselective synthesis of (2R,3S)-2—amino-3,4-dihydroxybutanoic acid, a naturally occurring amino acid isolated from the edible mushroom Lyophyllum ulmarium, has recently been achieved by chemists in Glasgow [Tetrahedron Lett. 2007, 48, 3?71]. A structural formula for (2R,3S)—2—amino—3,4-dihydroxybutanoic acid is shown below. 0 (1) Draw an arrow to the most basic functional group of (2R,3S)—2-amino-3,4—dihydroxybutanoic acid. 0 (3) Using any appropriate stereochemical notation write a structure for (2R,3S)—2—amino-3,4— dihydroxybutanoic acid. 0 (1) Write a structure for a diastereomer of this amino acid. i HOCHZCHC H002H 1D | | H N“; HO NH 2 . ‘2 H M. 8“ -ammo~3,4-dlhydroxy- butanoic acid i ..- {2R,3S)—stereoisomer a diastereomer d. (4) Complete the “minimechanism” below reaction below with structures for the initial reactant and the additional intermediate. 0 By what general reaction type is this reaction occurring?— 9 la :1. lim— pk La. ll (lei 1 9 ~— e. (4) Chemists in Slovenia recently utilized glucosamine hydrochloride (compound A) as the starting material for a synthesis of UDP-N-acetyl-muramic acid, a potential inhibitor of the enzyme MurC [Tetrahedron Lett. 2007, 48, 4403]. The structure of glucosamine hydrochloride is shown below. 0 (2) Using any appropriate stereochemical representation, convert compound A to its enantiomer. o (2) Convert compound A to a chair conformation. The hydroxymethyl group has been added to get you started. OH O tNljz i on compound A the enantiomer f. (8) ROADMAP. Demonstrate your skill as a synthetic organic chemist by completing this short synthesis with structures for the unknown substances B — E. 1. NaNH2 - B ———~————-a- CchHchchCCHchZCHg #J———L>H ’Lmd'a'cata' St 0 D 2. CH30H2CHZBF ; CH3CH2CH OH OH- H.. / E (CaH150) "—“—"' Cfl—C\IH Br CHQC H20 H3 g. ( r3) BONUS QUESTION! Scientists at the University of Wisconsin have HO" O OH developed a catalytic method for converting , OH fructose to compounds of interest for biofuel development [Chem Eng. News, June 25, HO OH 2007, p. 8]. D-fructose a diastereomer o (1) Circle the highest oxidized carbon atom of D-fructose. :- (2) Write a structure for a diastereorner of D—fructose. This is one of i 2 (number) diastereomers of D-fructose. ...
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