exam_3a_key - Chem 234: Exam #2 (version A) L‘ 7 April...

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Unformatted text preview: Chem 234: Exam #2 (version A) L‘ 7 April 2009 » Name: TAD ‘” l Student ID number: Discussion TA: Discussion Section number: Seat Number: (I) Put your final answer in the box, when provided, to obtain full credit. (2) Please turn off any electronic devices. (3) People caught using electronic devices will have their exams confiscated. GOOD LUCK! Point total: Question I (25 pts): _ : Question 2 (25 pts): _ Question 3 (l0 pts): Question 4 (l0 pts): Question 5 (30 pts): TOTAL POINTS: Out of ICC pts I. (25 points) Predict the products and indicate the relative stereochemistry for the following transformations. When necessary indicate the major product. (a) (3 points) HO Me _.__H_2Ni_, O H O (b) (4 points) (i) Fe, HCl @Ph (ii) NaOH F C NO (iii) NaNOQ, ACOH 3 2 (iv) HBF4, heat $Ml¢fl ‘Tb Pl“ Let {in “My 2 pg; we (c) (g points) KOH, H20 / H O OJLMe (d) (4 points) 0 SOCIZ, heat (iii) A/MgBr Me Me / Etzo } gm ‘04 wrflé ‘ (iv) H30+ o ‘ M m M {ya/(YT mfg {f L» mm.» f oiww M, 25%: (e) (3 points) O O H EtOJkOEt : NaH,THF l2. ‘4’ . (1‘) (‘ pomts) Me NH2 (i) Mel (excess), THF (ii) A920, H20, MeOH —, (iii) heat (g) (4 points) Me MeOZCWCOZMe NaOMe, MeOH —> 2. (25 points) Provide the necessary reagents to accomplish the desired organic reactions. Please number the steps and note that some reactions will require more than one step. (a) (3 points) (b) (4 points) [.3 new“ Acton (in HM! r4220”) L MGM; hast (iii) Limit. gig-,3 /©\/\/Ph Me NH 2 (c) (3 points) (d) (4 points) (e) (3 points) N3 \JJ‘OEt 0 Ph 0% Me (EGRU‘LWQW 9wfkh, Me Me (f) (4 POints) H50? (g) (4 Points) 0 mm 0 r 8 ‘ (IO points) Arene I, while not commercially available, can be readily synthesized from commercially available acetophenone. Please provide the reagents to accomplish this synthesis next to each arrow. Please also provide the structures of the intermediates in the boxes after each arrow. Br 4. (l0 points) Depending on the carbonyl substituent, LDA-mediated enolate formation can either be Z-selective or E-selective. Please draw chair transition states for each reaction that clearly explains the origin of enolate selectivity. (a) (5 points) 0 LiNu—Pr)2 Mew» : / + MKJLOMe THF, —78 °C 0M9 0L1 M Wham Q? N 3' l1 “W l - i l mlvm '5 ,li\\ , i / N‘w ,, n“- V (v, Jx i” m , \ . ‘I t M 2‘ A lii “brag-fl M%&Wbl2ld:::\fl M Mrlmcw’gm iiqué‘mned E’Amflmwa W3 fiWh :‘Wlmmrlalav5 (b) (5 points) 0 L.N(_ P) OLi OLi I I- l‘ 2 “46% + H Yk Me\/U\NMe THF, —78 °C NMeZ . / NMGZ 2 H >98 : 2 Me r; WALjSF 9L3 lW,MN\ ' Mr élxw o w m. M o "a ask: I! l W; ‘ Mi 2 a.“ lim7«/m Mwmm 4 i wmwmrs ‘ ,. i a _\ \- ‘ g é- a; iv '1 Mi Mi. ll)? .L“ i L : ‘X ‘9’” Aé'ilfilgl’hél ;_n:;_a;vt:\.MAl’lIte\ f It ‘ «gill ,‘ ‘ ‘ l‘._ _ Ml»: l‘l‘l’mfleixfiwa Wm {he L1 v” 3.3% “imam ‘ Wit Eh; Io z; ligolr‘ukhl) E 5. (30 points) Please provide a detailed arrow pushing mechanism for the following transformations. (3) (5 points) CQZH O O (i) NaOEt, EtOH EtOMOEt " .7 .7 7 , (b) (5 points) O O OH OH t-BUOAOAOt-Bu U N + 002 + t—BuOH N CH3CN ‘ H k : t-BuO O l2 (c) (5 points) In your mechanism, please account for the formation of nitrosyl cation (+Naflgz; ' M h MEUPh NaNOZ, HCI eUP —.___._> (.9 NH2 H20 NSN Emittme «53, 5N3» rN :0 j r fl g, ma», Maia? ’ .~ w ’13“ ’D/ f 6;? (/5; D 3N:"“"0 {73“ 5N 3"“3 [H «wan Mi fiwéa ’93 {3% m 7‘ M £9: 2 v" n w I“ “W ‘ ’ ‘ H (V, "L? 5%“: HQ) “1)? a .ng g a N a ,N 4N6 «M if? \éév v L3) M m g. M \u7 m “\ avg“? I3 (d) (5 points) In your mechanism, please explain the observed regioselectivity of the Hofmann elimination by drawing and analyzing the two transition states leading to both the major F and minor product. 6 Mel;D OMHe h ‘t Me M6 3 ea MeMMe NMe + MGVMG major pdt minor pdt Walk (9% QN ‘ r ‘P ' V (kw/r? W W‘ l4 m J [ Mflsm gall: l4 (e) (5 points) PhCN KOH,H20 0 ' PhiOK W W “on WW (A ‘ U‘ W ’ LEN 45"“ W n p; r M”?! \ 6X6: <—-—~ a WA { 3N “a “A, m, “Egg” M*©\ W m «m m. : m “a”? if 3 “ORE x31 @X‘MW ‘0“ I5 ‘15 on R E“ h, 9m“ W (f) (5 points) In your mechanism, please explain the diastereoselectivity of the aldol draw and analyze the transition states that lead to both the major and minor aldol product. 0U ‘ (i) i—PrCHO 0” O M —’ i-Pr)\|/U\NMe Me2N&/f (m) H4NCl(aq soln) Me @ 2 @ ZEWS‘S 0E: L} @113 “3;, be} w- , . $15191“ Iggy» WW I gym-t m} = w Fix-7"“ i Lahmwmwaw‘” Mambo ma am; 3 L r m; , 7 :F L i ii Mm, 3 Z, r’i @ ogia a M My} I6 ...
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This note was uploaded on 04/14/2010 for the course ENGL 104 taught by Professor Osbourne during the Spring '08 term at A.T. Still University.

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exam_3a_key - Chem 234: Exam #2 (version A) L‘ 7 April...

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