140C FINAL SP2008 KEY

140C FINAL SP2008 KEY - Chemistry 140C (Finn) Spring 2008...

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Chemistry 140C (Finn) Spring 2008 – Final Exam V1 This exam in total accounts for 50% of the final grade. Time: 3:00 – 6:00 pm Mark your final answer clearly and completely erase or cross out irrelevant information. Remember: Exams written in pencil will not be re-graded! Additional pages are appended at the end for your convenience. Please indicate if your answer should be found at the end of the exam. Good luck! Your Name (please print): KEY Your ID #: __________________________________ Question #1: ___________ / 54 Question #2: ___________ / 66 Question #3: ___________ / 30 Question #4: ___________ / 20 Question #5: ___________ / 20 Question #6: ___________ / 15 Question #7: ___________ / 25 Question #8: ___________ / 30 Question #9: ___________ / 40 Question #10: ___________ / 30 EXTRA CREDIT
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Name: KEY 06/13/08 Page 2 of 14 1. (54 points) (a) Circle the products that are possible (even if unlikely) from the aldol reaction shown. 10 points O + H O Ph NaOEt (cat.) EtOH O Ph O H O Ph H O Ph Ph All are possible 80 °C (b) Write a detailed, arrow-pushing mechanism for the formation of the major product. 44 pts max.; identification of the wrong major product loses 8 pts O + H O Ph NaOEt (cat.) EtOH O Ph H OEt O Na H O Ph O O Ph Na EtOH H EtO NaOEt –NaOEt O Ph OH H NaOEt OEt –NaOH O Ph This is the major product because it uses the aldehyde as the better electrophile (much less hindered) and the ketone as the nucleophile.
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Name: KEY 06/13/08 Page 3 of 14 2. (66 points) For each of the reactions shown below, circle the favored product. (a) 6 points O H + NH 2 N C + CH 3 CO 2 H O Me 2 N O N Ph H N O NMe 2 O O O H N O NMe 2 O NH 3 CH 3 O 2 C salt O N Ph H N O OH O N H N O NMe 2 O Ph O Ugi Reaction (b) 7 points O O CH 3 CH 3 N H NH HN O O 1) HCl, H 2 O NH 2 N N H O O CH 3 CH 3 N H NH NH 2 2) workup with base H 3 CO N H NH HN O O NH NH NH O H 3 C Here s the mechanism: O O N H NH HN O O HCl, H 2 O O N H NH 2 NH 3 H NH 3 NH N HO H NH 3 NH N H 2 O NH 3 N N NH 3 N N H H deprotection of acetal and Boc groups proton transfer O N H NH NH 3 H H proton transfer H 3 O H 2 O NH 3 N N H basic workup NH 2 N N H (c) 7 points H N + O CH 2 O + isopropyl alcohol (solvent) 50 °C CO 2 H (catalyst) O N O OH HO N OH
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Name: KEY 06/13/08 Page 4 of 14 (d) 5 points HO Cl NaOMe MeOH O O O MeO OMe (e) 5 points NH 2 OCH 3 NaNO 2 HCl, H 2 O NO 2 OCH 3 NH 2 OCH 3 N 2 OCH 3 Cl NH 2 O O H NH 2 OCH 3 NO 2 (f) 5 points OH 1) TsCl, pyridine 2) NaN 3 in H 2 O/MeOH 3) LiAlH 4 , Et 2 O 4) acidic workup NH 2 N 3 H N NH 2 NH 2 O S Cl O O TsCl = (g) 6 points O HO OH HO HO OH 1) 2) H 2 O, HCl (cat.) or H 2 O, ZnCl 2 (cat.) (ZnCl 2 is a Lewis acid) O O O O O O CHO H OH H HO HO H H OH OH O O O (excess)
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140C FINAL SP2008 KEY - Chemistry 140C (Finn) Spring 2008...

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