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Unformatted text preview: Chemistry 504 Exam May 13, 2009 Name: E g E l Score l. (10 points) Identify compounds A and B, indicating stereochemistry. Me o o\/k CH3CH2C02Et,
CH0 LDA, THF, ~78°C p—TSOH (excess)
C6H6, reflux ———-—-————-——-—-——--*- B (CGHIOOZ) i \ 'W/Me
Ma»<}’c 2. (44 points) Give the major product and indicate stereochemistry where appropriate. a) b) if d) H3C CH3 Cl/\ COZH COZCH3 NaOMc, PhCHO I @631 COL/mg
m.
J2
A a?
’) C 1M +
m 0 a 433mm VA", 'i‘ rams
( mix-200v" o—xylene, 120°C MeO OMe "”0TBS ‘ LiCI, iPerEt
CH3CN, 25°C _......._——-——.————-—-—~—-> 1) ACOH, H20, 100°C
2) NaOH, H20 1) MegsiCHQCOQMe (1.0 equiv.) COQMQ 1) LDA, THF, --78°C
2)
0 \‘v‘ ‘
Meg(tBu)SiO\\\ ”I”
”’03i(tBu)Me2 k) OEt NaOEt/EtOH ._....__——-———-—-——-> 3. (36 points) Three synthetic transformations are shown in the retrosynthetic format. Propose reaction
conditions or a series of reactions which could effect the synthetic conversion. You may use starting materials with five or fewer carbons. 3)
/ /\/\O\>\/\/COZM6 :__—:_::> __.._—— 0 B
M o C
/\/\/OSitBuMez ( i
H + COZMB
H 19 A + SMe2
H (+3
Pth
+ ~ W is Betti fiat?) 426: ”WM”: 7,”) 6 )H/VHPALj 48;? NC? M/W A u on BALMEEFQ) THF) etc , 91% W i) LDA ,THF, e???) /W W ”/W CHO OMe 4. (10 points) Propose a mechanism for the reaction shown below using the curved arrow formalism. ...
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