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3_19_2001 - NAME CHEMISTRY 130B(B.H Lipshutz Final Exam 4 4...

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Unformatted text preview: NAME CHEMISTRY 130B (B.H. Lipshutz) Final Exam March 19, 2001 4+4+6+5 19 15 15 5+10 15 3x6 18 3x6 18 . 15 15 . 9+16+7 32 extra credit I I 1. Predict the major organic product from each of the following. Indicate stereochemistry where appropriate. (a) o a sick: [I H u Ill), (b) orM (C) (d) (e) (f) (g) I. WIQ'W 2. P06, 0M0!» —————————-—_—§ 3. H'LNNHPh l- PBra. 0147.041 2. H2! 903164.003 qymoh'ne 3. H2N+, cat. 11* 2. Provide the reagents (over the arrows) needed to effect the following transformations. (6!) Z\ i aha ————> W (19) am 0 N\\\\ _.._..__. Who D D (C) ¢ \ Dig,» coo H [:10] / 600 H 3. Starting with 1-hexanol, devise a synthesis of n-heptyldimethylamine using any reagents of your choosing. steps WOH —__—> WT/ 4. Compound 'X', which contains no nitrogen, gives the following IR, NMR, and MS data: MS: m/e (relative intensity) 166 (M+, 5), 164(15), 135(11), 133(33), 129(100), 92(9), 90(27). nu: , , T T. T...__ y ‘ l l ‘ i -v,........_;___..-._T._-_+.._.T_._..,._ 4..-- .i...s.__....__..._. u. u ,.__.s_._._- a”. t r—""”—"'.'"""” _. 7' _————-...-L_. _-.._..._.__.i_..-._.A__.,i -._.-...- , .-.i..- IXI = 2:: (a) Label 3 characteristic peaks in the IR spectrum. (b) From ALL of the data given, suggest a structure for 'X'. (c) Give the structures and charges for the seven peaks observed in the MS of 'X'. (1) (2) (3) (4) 5. When 2S,3R-2,3-dimethyl-3-hydroxypropanoic acid lactone is treated with LAH, a more polar nonracemic product 1 is formed upon workup. Exposure of 1 to catalytic acid in the presence of cyclohexanone in a reaction flask fitted with a Dean- Stark trap and refluxed in toluene leads to final nonracemic product 2. LAH cat H“ ——-—> —-—> 0 (then 0 workup) (l O 1 2 Give the complete structure for the starting lactone above (i.e., substituents and appropriate stereochemistry). Provide a structure for product 1 (in the box above). Suggest a structure for product 2 (in the box above). Assign the absolute stereochemistry for each chiral center in 2 and compare with those in the starting lactone. Are they the same? If not, why not? 6. Conversion of a ketal to a ketone is usually accomplished with aqueous acidic conditions. (e. g., 3 to 4). However, acid hydrolysis is not effective with dithioacetals such as 5. Instead, alkylation on a sulfur atom with methyl iodide in the presence of water achieves the desired result by an otherwise identical cationic mechanism. Provide a mechanism, therefore, by which 5 goes to 4 using the conditions shown. 3 ma“ CH3! 3 __., <—— 8 H20, THF 5 7. For the following reaction sequence, excess (x’s) amine is required to consume the acid (HCl) given off in the formation of the amide product. Alternatively, the ”Schotten—Baumann” method can be used to minimize loss of this valuable amine. Provide alternative reaction conditions that reflect this method, and a mechanism for the generation of the amide under ”Schotten-Baumann ” conditions. Wool + X's 0"? LC" Whip (opt. pure) Alternative reaction conditions: Mechanism: 8. In each of the following. there MAY be an error in the chemistry as shown. If so, in one sentence/ phrase, indicate the error. Should the overall process/ reaction/ name be correct, insert ’correct’ in the box to the right. 0 1 mean 0,. 0 ('7) W aw N + ”0% | swifiiamm 9. EXTRA CREDIT; you must provide the fully correct answer to receive these 20 points). Compound 'Y' gives the following IR, NMR, and MS data: MS: m/ e (relative intensity) 121(M+, 76), 95(100), 26(44). Suggest the structure for 'Y’ " ”’2’" f // i H NMR an m ,. w 2 3o ._ V . , f 111 an; 2 5m . 2.4m 3m 200 W‘ 9‘ a 7 ' s 5 1 3 z . WAVBJUMBB CM 3000 2500 20000 1500 1300 1100 1000 900 800 700 650 6 EM“ -—————=‘-—-,-==‘i§==‘=“"‘=‘ ” ““ Ewe ““ "’=’="”% ‘ 2 2:; wfigfifig 2222' - E- 2.. 222E ' EEEE E: _2:. mggngE E 2 :; wgfiifigi =E2=—22E22E§22E3EE22 ag-EEEEEE j EEEEEg Ezm=E§flE§5fE 2 Egg-EEEQE ; EEEE2; E==EE222222 222E222 2E§E§222§E§22 REE E_EE =2EEEE§§2222 222* E22222-2— E 2amEeg222EEEE .2 - E EEEEEEQ =E22EEEEEES§EE2 agiiéggmfifgfifi 22:: 2.22m IYI ...
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