FinalKey_Wi02 - Art‘s NU Chem 210-2, Winter 2002 1. (24...

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Unformatted text preview: Art‘s NU Chem 210-2, Winter 2002 1. (24 pts) Complete the following reactions, be careful to give all the major carbon-containing Final exam products, starting materials, or reagents. Clearly indicate the stereochemistry when relevant. If there is no reaction, say so. b) d) 0 ME” (1 O © 0 Own” ) gout) 0—5 tap 2,) Lcccu 3) “3019‘2’0 1) was) K7 2) Mac» —-—————-—-> 9 Sins 4.) “30* 3 “LO O W oi O /fi\/C€') ’O-‘gfk () ML Jag-39" z, h’aOH «A. 2) (+90; (M at 4) FROM ____v——— OO$OH MM)02N Oil—filth )w} (5 “401+ 01-10 3n. {165 M 0 "—~ 0 cu} Q} 1) 1 CHaBr, FeBr3 cat. 2) KMnO4 hot, cone. 3) CH2N2 1) 2 PhMgBr 2) H3o+, H20 3) Ph3P=C(H)Ph 4) H3o*, H20 1) Clz, AICl3 cat. 2) KOH fused, fl 3) Brz 4) KO‘Bu excess, heat 6) H307 LXUSL 2. (24 pts) Complete the following reactions, be careful to give all the major carbon—containing NU Chem 210-2, Winter 2002 Final exam products, starting materials, or reagents. Clearly indicate the stereochemistry when relevant. If there is no reaction, say so. -0 a @an Jazo a) Z MBr ol “‘ a) ‘06€ 7 go, 6.2m. C” o H m; “l M 1)%Hac(0)er, FeBr3 cat. _ K H 2) NaCrzO7, H2804, heat [/0 3) SOCI2 b) 4) LiA|(OtBu)3H AV (its M 1) N H d1H a . / OD“ s \o, 0 3) H20 ) H30.f 4) CH3C(O)CI, AICI3 excess, heat C) 5) BH3-THF /——o [ H'CQ C0 C-«CL um, OH )6 ) J } OMe 2) Nu} J 05 mwjpgowc d 4') Na“ NH2 ) in M4: ( Hwflmo) é) HL’NL‘ORU‘W‘ 591W MQMA‘flJU-n-L Domgg‘m) 4839‘))>o w (ill Quesfla Tk%hmm W W McMOH (an u. m “1&5 e) OH {- m . 3) C(QNL )49 0Q: CHLI¢/'6\/C«Ce, 9’“ ~ f W 4) HZO") [+20 [wok Sun 1) Na (excess), NH3 (liq), -78°C HO o EtOH 2) H3o+l H20 m cfio H 3) O3 (excess), MeZS (excess) h 46' 4) NaH Hf)». “PM Hem NM 5) MeNHz (excess) 6) LAH (excess) 7) H3O+, H20 HOJ‘M (+0, NU Chem 210-2, Winter 2002 Final exam 4 3. (20 pts) The Wittig reaction is quite useful in the conversion of an carbonyl compound into an olefin. In one special case, the Wittig reagent Ph3P=C(H)OMe can be used to convert a carbonyl compound into another carbonyl compound that is one carbon longer than the original carbonyl compound. Propose a complete mechanism for the synthetic sequence shown below. Show all the proton transfer steps. Hint: As you have learned in class, the hemiacetal on the left is not stable and is in equilibrium with a compound. For showing proton transfer, because the Wittig reagent is not quite stable to water or other protic species, the hemiacetal will act as its own proton shuttle. For easy notation, use the abbreviation [3H to denote the hemiacetal where BH can give up a proton to be H, take up a proton to be +[3H2. O OO\ 6 0“ 1)Ph3P=C(H)OMe H0 Use g H: 5H —> g 2) HCI. H20 *1 3‘“ H" for proton transfer purposes NU Chem 210—2, Winter 2002 Final exam 5 4) (25 pts) Propose a curved arrow mechanism for the following reactions. Show all the proton (\I \ Brz, MeOH / a) (10 Pts) n/ F" Q NazCO3 (a mild base) MeOQOMe 2 y Noll CO 3 9 l-g-Pt‘l Mow transfer steps. .. 0U”) : f:/OH—L (+504, 26% 2. My \mc mg 2 \Ofl‘é 03c- ‘ V“ 0a» 0% l “301' l f x 6? \/ 4+ 41;; YKOH—L’L We 09c OHL 0” a» Hm? 0H 2 ~I L 6 L“) H201" NU Chem 210-2, Winter 2002 Final exam 6 5) (15 pts) Propose a curved arrow mechanism for the following reaction sequence. Show all the proton transfer steps. /CI *3} O O Na2C03 (a mild base) then acidic work up 0 O NH 2) PCI3 I 3 AlCI,CH,Heat S ‘ > 3 6 6 b W559“ \V O \ @Nhn 157:5 V M475 NU Chem 210-2, Winter 2002 Final exam 7 6. (20 pts) Dofetilide (Tikosyn®) is a Pfizer drug for the treatment of cardiac arrythmia. From benzene, methylamine, methane sulfonyl chloride, and any carbon-containing starting materials with 2 carbon or less, propose a synthesis of dofetilide. You may also use PPh3, the Swem reagent (dimethyl sulfoxide and oxalyl chloride), NBS, tosyl chloride, pyridine, PCC, mCPBA, peroxide, and any inorganic reagents. Hint: Methane sulfonyl chloride is exactly as tosyl chloride in all of its reaction N \S/ \ / r11 0” 00 ”S“o m 0 ° N dofetilide methane sulfonyl chloride /S=O __ || ll 240 H 044* OJKH 1/7/61)” 9%, {EVE '+ 475'” Mg 0/3/ Merge» o w ' o H 9’} HyofiHu) MW? p..w. [\/®__U_%~ o \l —9 we A N02 /NH7, , - T1 4 DJ Z‘AHC—l A NU Chem 210-2, Winter 2002 Final exam 8 7. (22 pts) In certain cases, nucleophilic aromatic substitution can occur under mild condition when there is a good leaving group on the aromatic ring and a good nucleophile to attack such an aromatic ring. For example: LG MeO®ONa O —-——————> CE 0 LG = I or OTs N02 N02 OMe Suggest a sequence of reactions for the synthesis of methoxythyroxine from tyrosine, going through the tyrosine acetamide ethylester as shown below. You may use benzene, acetyl chloride, ethanol, and any starting materials containing 1 carbon or less. You may also use ethylene glycol, TsOH, the Swern reagent (dimethyl sulfoxide and oxalyl chloride), NBS, tosyl chloride, pyridine, PCC, mCPBA, peroxide, and any inorganic reagents. Your synthesis must go through the tyrosine acetamide ethylester or it will not work well. Elaborate why this may be the case. 2 - FD" 01+] 24““ Hint: Your life can be a lot simpler if yout 'nk diazotization. 1: OH ‘rp’ m /0H “Ella l out I I QM % o 0 fl 6 i /C Q‘ Ma} C T NE E o g 1 I o l | r g HO O HO O OH O a. ———> -—> Meo 0 mm @051 NH2 H N o ( 16V 2 2 Tllvn L NH2 WNH I I OH O f _ r.-. x‘ m \ M ,- Tyrosine " Tyfifine aoetefn'ide ethyl—ester r Methoxythyroxine Thyroxine a ~ « «15 MM, Zfifis ”“” NU Chem 210—2, Winter 2002 Final exam 9 Bonus (5 pts): Methoxythyroxine is the methoxy derivative of Thyroxine, a hormone which control the metabolic rate in the human body and the lack of which lead to hyperthyroidism or goiter. Show how would you modify your synthesis to arrive at Thyroxine directly. E C» r" 0 l 0 I /I\ g a ,l-\/\ \/\\ ‘L e l) j, 0 KO 0 r K? 3%“; 0/ I f. "‘0 ' L "H; awn“; "' 3 W; f‘ 9‘ uf L OWL (1: D 0] C MD), 0 k 5 l O a V + War—— w v) 02 (w x H i, .L. 7 no; oi tar/r; ‘ [0L mm, 4) “wtjlwtlksm MWw-fim g) f; Kngegp W11- pvmb‘ow 8) (15 pts) Recall that aspirin can be made from phenol Via an electrophilic aromatic substitution. In the presence of a strong Lewis acid such as AlCl3, aspirin itself will undergo the following isomerization reaction ( essentially a Friedel-Craft acylation reaction where aspirin is its own acylating agent). Propose a curved arrow mechanism for this transformation. 0 O O O OH 0A Aspirin 0L0“ Cf.) jk— 0H 2 fi-ow /\ / HAW” /0 LE [/0 n O o" l 637‘, V\O'~—AQ Ce; ‘15” 259 f (5 o Cg M /M@ 2,342 P, 9W Cs M 0 H 09mm at 1:. M j /{0( logo“ my AWOH O “Oli'fl e o\ 25,; \ , 2. H at Am 69 ~ \ho/ \ \OQ’ 4% ?\'o-~za:p J; \Aéazg “Cg . (fl @ C c.) I E O _, @ ‘ Li 0‘ w /\L01v + .1 ‘ I :m 0‘: g ( \_ \ /ILW @ “— (Wk 2, 9C” \ waldo mm W Qua. t; m m Mas /:’ \W‘OW- gvy P F\01+ gAfl/Tcam WA ' ) ( i‘OH /fi~0w 0 R I 1 6‘ ,_/‘\Ol} / \ \.,; i O . \ “M‘ Mai, j A EnJoQNU) m [055 0k. (2, W gut/xx ‘ p L M\ 176;“, :ULIM» » of? ‘ 0% j I? l 4‘» /fi‘0u A | :1 0 Ca.— \ \ ‘04!» AL *1 (ilk- \ é. / l «av—F” I , 0 OP 5/5.: V\0 (rm wnfukaéwm, 30% NW Q’W : H - CL NU Chem 210-2, Winter 2002 Final exam 10 9. (20 pts) From 1,2-benzenediol and any carbon-containing starting materials with 2 carbon or less, propose a synthesis of the following molecule. You may also use PPh3, the Swem reagent (dimethyl sulfoxide and oxalyl chloride), NBS, tosyl chloride, pyridine, PCC, mCPBA, peroxide, and any inorganic reagents. You are not allowed to use Corey-House in this synthesis. 0 “fig 5’qu HO O 1,2-benzenediol #0 1) 9% \/ (+0 2») Kimmy/c a) Mr Jays < a ‘0 ...
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FinalKey_Wi02 - Art‘s NU Chem 210-2, Winter 2002 1. (24...

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