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2_4_2000 key - NAME,5 E Y I 12 IO 231’ 2 8 5 IO 23 3...

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Unformatted text preview: NAME: ,5 E Y I. 12+IO+§ 231’ 2. 8+5+IO 23 3. 192+ 3+§+§ 30 4. 20 20 CHEMISTRY 130B Exam I February 4, 2000 lOO WHEN SGENCE CATCH? U? To SPORTS 1. For the alkyne below: 1. BH3 _ > M +2 } 1. n—BuLi 2- H00- uxn HYH CdPtIHOg+ NZ" 2 EtBI‘ NaOH ‘ 3 3. Na/lq NH3 Li Y\ 6440 '+ >/K 4 >4“ 2+ (3) Predict the major product for each reaction sequence (put answers in the boxes). (b) Give an (arrow pushing) mechanism for steps 1. and 2. (only) in sequence “Z”. (c) For step 3. in sequence “Z”, one of the intermediatesis a ‘radical anion’. Draw a 3D orbital picture of this intermediate. (b) mechanism: p n-le-i Mama” to >A = *H A» ‘- ”.2; >— ~ (c) 3D orbital picture: g 2335026/ (w W mug w/ Mans) 2. When 3—butyn—l—ol is treated with 1 equivalent of sodamide, followed by methyl iodide, the desired product 3—pentyn-1-ol is NOT formed to any significant degree. 1. Na N Hz 2 0H ‘ / A/ 0H . é A/ i y 3 sodamide X - / 3 g 3-butyn— 1 -ol 2, Mel 3-pentyn— 1 -01 (a) Give the structures for the starting material and desired product, as well as for sodamide (in the boxes above). (b) Given that a reaction other than the desired one above does indeed occur, predict the actual product to this reaction (put answer in the box below). l. sodamide 0 M e 3—butyn- l-ol _____..__. // N { 2. Mel (c) Explain briefly why the desired reaction fails, and why the alternative reaction takes place. 4 ”OH Mm s m t' K NI} (Ma/n A) 10 (“m (egg ~;§). 3%. fly bag ma :fm an “(mm Mwn m1 l mm W 5 n m QM 0 k! y] aldld . 3. On the chart below: 61 51 nods w 3 >Lx:_<OCH3 0 W. 5W b OCH3 A c PP'" g 3r 5 It 3 z z o (a) Sketch the 1H NMR spectrum for compound A and assign all peaks (label ‘a’, ‘b’, etc). 2 (b) Draw the relative integration for each signal. 3 (c) What is the multiplicity for the signal due to the methine proton in A? SMSVX 5 (d) How many magnetically distinct carbon atoms are present in A? Q (e) Which carbon atom in A is likely to appear furthest downfield in its 13C NMR spectrum, and what will its multiplicity be if it is not proton-decoupled? /O’ b § “‘Cl/\O__ olvz/ (LT H 4. Starting with l-hexene below and using any reagents, propose a short synthesis of Z—2—heptenc (hint: recall the main topic of discussion thus far!). Show work for partial credit. 6 7 ' CH3\/\/\1( H CH3\/\/\2( H H CH3 ZO ifiz Wan ...
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