C357_Exam_2_Key_Real - Cornell University Chemistry 357...

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Unformatted text preview: Cornell University Chemistry 357 Summer 2005 Examination 11 June 24, 2004 Instructions: Read all questions completely before answering. If the question is still unclear, be sure to ask for clarification. You may find it helpful to first answer those questions that you find easier and then return to those you find more difficult. Good Luck!!! .- - ‘- m- — - _ _ _ — _ _ - - — _ Name: E E I Signature: Page 1 of 9 1) (18 pts) Provide an IUPAC name for each of the structures shown below and write your answer on the line to the right of the structure. Or, when given a name, draw the appropriate structure on the line. Be sure to include any required stereochernical designations. / A) f— 511159474, — 4- MEFHYL c‘fCLoHEXA-NE 01 24+" '45 WYL cTcwHW n.) ~f — ETHENE B) (+523 ~g !'~ METHYLPSNTYL) ~th - HEXADIEN 2. Cl C) \>—< (1%)'I‘BIZDMO-I“CI+LDIZ0‘Z'HEU L-l-BerNE: Br D) zfi We — - 8120540“ 2~ HEXENE BrN‘w‘ H E) w (lffl‘CYCUHEfiIL‘ I-PRaPENE H H ' CH3 ‘12) H Br (2,52 442) 2'4 - Dagwm— 3 "CHLOKOPENmNE H Cl H Br CH3 ' 0R. (22,95) Page 2 of 9 2) (27 pts) There is a dimethyl diene (a diene chain with two methyls attached somewhere!), call it Compound X, with the molecular formula CgH14, that is first reacted with one equivalent of Hg on Pt. The two achiral products from this reaction (each where one single bond has reacted and the other remains unreacted) are then subjected to two further (but separately done!) reactions, producing all of the carbon~containing products indicated (and their stereochemical relationships to each other are also noted. Based upon the reactions and product distributions, draw the structure of Compound X and the structures of all of the products. All drawings must be drawn so that their stereochemistry, ifany, is unambiguous. Ambiguous answers will graded as incorrect. Structural Isomers Compound X Product A Product B 03H“ CsHm CSHIIS Achiral Achiral 009‘ 989$ :3 E E E? E 8 U! W! M m g E Chiral Product an r a . 3 Achiral Product Achiral Product Chiral Product Br M Chiral Product Chiral Product PW Enantiomers Page 3 of 9 3) (12 pts) Determine whether each of the following structures is meso. If it is meso, write “meso” on the line below it. If it is not meso, write “no” on the line below it. 0 H H0 H B) C) HO H H OH , H OH CHZOH M550 No No D) E) F) H3C CH3 M ES 0 No N o 4) (16 pts) 21) Propose a reasonable mechanism to account for the formation of the following observed reaction product(s). H Cl H b) Are other isomeric products possible for the above reaction? Yes ® (circle one) Page 4 of 9 5) (16 pts) a) Propose a reasonable mechanism to account for the formation of the following observed reaction product(s). O 1) 03 '——> H 2) (CH3)ZS H _- \Heckmism : @ C’o‘ /\ M“ 1Cyl own '9 b) Are other isomeric products possible for the above reaction? Yes No (circle one) 6) (16 pts) Propose a reasonable mechanism to account for the formation of the following observed reaction product(s). b) Are other isomeric products possible for the above reaction? No (circle one) Page 5 of 9 7) (12 pts) For each of the following reactions, determine how many isomeric carbon-containing products would be generated from each reaction (carbon- containing means that its carbon skeleton is wholly or largely derived from the compound to the left of the arrow in each reaction). Write the number of products on the line to the right of each reaction. A) H3C H -— H2 l Number of unique, isomeric carbon— Ni containing products that are possible. H , H3C 5% B)H3C,CH CHB — HCI 3 Number of unique, isomeric carbon- containing products that are possible. chnzc CH3 as C)H3C,CH CH3 —— HCl 57 Number of unique, isomeric carbon- containing products that are possible. Hscflzc CHZCH3 O W ’H 0-0 . . . D) C] 2- Number of unique, isomeric carbon- containing products that are possible. CH3 E) HO 6’4 ' CH3 H2804 Li” Number of unique, isomeric carbon- HZO contalmng products that are possrble. OH F) l-I3C 1) BH3/THF 1 Number of unique, isomeric carbon- 2) H202, NaOH, containing products that are possible. H20 Page 6 of 9 8) (I 6 pts) a) Propose a reasonable mechanism to account for the formation of the following observed reaction product(s). CH212 —— ———————-—> Zn(Cu) b) Are other isomeric products possible for the above reaction? N0 (circle one) 9) (16 pts) :1) Propose a reasonable mechanism to account for the formation of the following observed reaction product(s). Hgso4 HO -————> \ H20 ‘9 ‘0: “~92? m "r LY -—-> mt b) Are other isomeric products possible for the above reaction? Yes No (circle one) Page 7 of 9 10) (20 pts) For each ofthe following molecules, clearly circle any atom which is a sterocenter. Next, determine whether your indicated stereocenters are R or S and write the designation next to the circled atom. If an circle or designation is ambiguous in any way, it will be marked as incorrect! Please make sure your answers are clear! Page 8 of. 9 ll) (l5 pts) The following amino acids are the 21 commonly occurring amino acids in biological systems. Circle each amino acid that could, in theory, have a diastereomer g an enantiomer. Once circled, write an “E” next to the circle if it is possible that it has an enantiomer and write “D” if it could have a diastereomer. If it could have both, write both letters next to the circled compound. Common Amino Acid Structures fl 0 ‘x \I / || \ l o 9 ""“‘ || \ l‘lgN—(EHC~OH HEN —cn—c—on CHE I 0 II 'lzN—(IZHCH-Ol‘l 2N_TH_C__..OH- ] (LH / CH2 J $HZ l CH2 2 I 3 ¢H2 / \ if? 0 xi 1 ,. a ’ C t 0 / Alanine E NH ' I NH2 If"?! I / \4/ E 0H /,/ E Asparagme ’ . . Aspartate Arglnme Eek “x A C”) \ . || 1 HEN_CH -(L!_0Hll HEN—(III! ~C—-OH\ figN h—CIJH—C—OH HEN —(|:1-1—c—0H CH2 -' (13—13 / f“: H I ,3 CH2 _ . , .x' / | / G lye: ne ‘ ' E / (3 =0 (x . v- / .— Cysteme E / F: Glutamate 0 " ..._\ 0.x Glutamine II || “‘\ inn — on -c —on\_\ HEN _ (in _ C __ Q ‘ / cfi \\ cn2 } ETHII‘I‘CH3 J HQN —cH -c—01 .i " ' I; CH2 N \ / CH? x“ I / | .x' CH *Cllg /* /« CHJ // I _ s x E 9 CH; //E- H HQN — CH - 0 Leon N | x \ CH2 Proline Phenylalanine W\H/ Methionine g . HEN 4|:ch —0H CH2 ZN—Cl-lw-C— (Enron CH3 / Thrconine EJD ll ,\ H2N — CI-l — c — II 0143 1—: Val ine F; Tryptophan OH ...
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C357_Exam_2_Key_Real - Cornell University Chemistry 357...

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