W08 midterm2 key

W08 midterm2 key - Organic Chemistry 30B Winter 2008 EXAM II Page 1 I CONCEPTS NOMENCLATURE 1 a(10 points Give an example of a carbocation

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Unformatted text preview: Organic Chemistry 30B Winter 2008 EXAM II, Page 1 I. CONCEPTS / NOMENCLATURE 1. a) (10 points) Give an example of a carbocation rearrangement seen this quarter: , _ . (17 0» Ho 0% H 9 H (7 I ‘ H ( kéo 0&1 b) (6 points) Rank the following compounds by increasing reactivity with a carbonyl group: We - 6’ boo ( ) MeLi KCN MeOH A B 9 Trend: C < B < HK c) (9 points) Illustrate by an example the following terms seen in material covered this quarter: >-: o \W , Wittig reagent: \ _/_ ~ / v: i 7 »_ ' 7 >’( Acetal formation: 7_ 2/ E OH, H t w / ' E are “47 / >< 0 i2 )6 :0 H> I ( Mia/WM ‘ 3 Organic Chemistry 30B Winter 2008 EXAM II, Page 2 ame II. REACTIONS 2. (25 points) Draw the major product for the following reactions (if there are enantiomers or diastereomers formed, show only one, but pay attention to stereochemistry where needed!) Aqueous workup (e.g. H3O+) is implied after each step where needed: a) 1) PhLi 2) H2304, heat ——————> 3) 0804, then NaH803 4) HO; 19) 1) SOCI2, Pyridine 2) MeONa ——-> 3) RC03H 4) PhLi 5) FCC 1) HOCH20H20H '/ H+, mild heating 2) FCC ) EtMgBr / ) TsCI, Pyridine ) EtONa ) H3O+, H20, 25 °C QH , OH 1) 2 eq CrO3, H2804 F4 2) 2 eq MeMgBr ’ ——————-——> 3) H2804, 25 °C 4) PhMgBr 5) H2804, heat 3 4 OH 5 6 d) 1) MeSOQCI, Et3N 2) KOt—Bu —'—> 3) RCOSH 4) MeLi 0“ 5) PCC Organic Chemistry 30B Winter 2008 I EXAM II, Page 3 "(g—— ' me III. MECHANISMS 3. (25 points) Provide a complete, detailed mechanism with curved arrow formalism for the following reactions. Each step must me explicitly written down, i.e. every attack of reagent, bond breaking and bond forming steps must be shown! a) (13 points) \ *1 O 0 if CH0 1 - L/ t / \ L2 ‘7 \j‘ H30+ ,/‘\ L/ l 4" (show also byproduct) 7/ “H 0 {H ) t + + » 0% K /”\ W (y‘p ‘ +1 (b ,‘ - :0‘ ; H’U 29H .¢0 U9 aim- H10, ‘5: ‘4 ’C/‘\'/»J } “‘7 H \ ,J‘\ mmi’fi .é M a \ ( \ I l Z l H “L 7“ [ / ‘ + 2 \‘J HLOZ b) (12 points) A 9H R\ [l ILA 'i 3 Cl (/ U "“ 1/ » X .s 7 I bl //\ U7 I 5 MM» “\u A it w Organic Chemistry 30B Winter 2008 EXAM II, Page 4 IV. TRANSFORM 4. (25 points) Devise a reasonable synthesis for the following compound from reagents you are familiar with and the starting materials provided: Note: do no “invent” new reagents or reactions. Use only those specifically taught in class or previous quarter's reactions. There should not be more than 10 steps necessary in these syntheses, although longer ones may also be correct. a) (12 points) ' :7 ['“nawé I “ij’fl‘ws/ e")? D OH w I f um Mf/HVW/ \\K O L” ‘ / PL M {1 (4: W Organic Chemistry 30B Winter 2008 EXAM II, Page 5 Na b) (13 points) k T [7,4, L; K (W WQJZS/gl- C; H E ’ ’3 /J\/\ 0 > ” 619 Ct; H30 ...
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This test prep was uploaded on 04/05/2008 for the course CHEM 30B taught by Professor Rubin during the Winter '05 term at UCLA.

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W08 midterm2 key - Organic Chemistry 30B Winter 2008 EXAM II Page 1 I CONCEPTS NOMENCLATURE 1 a(10 points Give an example of a carbocation

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