Exam1Key - Name _ W.09.215H Ex a m N o . 1 Page 1 1. The...

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1. The following reaction sequence might be the sort of scheme proposed for the Honors Cup competition. Br Br Br Br Br 2 CCl 4 Br Br NaOCH 2 CH 3 Br HBr Br Br P Q R S The problem with this is that the elimination reaction ( Q to R ) is not terribly selective, and gives a mixture of products. R R 1 R 2 R 3 Using the 1 H-NMR and UV spectra, below, determine if the major isomer is R, R 1 , R 2 , or R 3 . Justify your answer. Major product: circle one: R R 1 R 2 R 3 Clearly state how your choice is consistent with the spectral data as well as how the other three choices can be ruled out based this data Name _____________________________________ W.09.215H Exam No. 1 Page 1 16 R & R 1 – no conjugation to alkene; therefore, would not expect UV-vis peak at 300 nm R 3 – CH 3 group would appear as a singlet in 1 H NMR spectrum, no singlet is observed; also R 3 shoud have 3 groups of non aryl hydrogens (not 3 as observed here) R 2 – alkene conjugated with aromatic ring; therefore, expect peak at 300 nm. Predict the following NMR spectrum. Peaks a, b, and c differentiate R 2 from R 3 . Br a: doublet (~4 ppm) b: doublet of triplets (~6 ppm) c: doublet (~6.5 ppm) d: doublet (~7.2 ppm) e: triplet (~7.2 ppm) f: triplet (~7.2 ppm) a b c d e f
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Name _____________________________________ W.09.215H Exam No. 1 Page 2 CO 2 CH 3 (H 3 C) 2 N (H 3 C) 2 N + J. Am. Chem. Soc. 2005 , 127 , 11616 2. Complete the following Diels Alder cycloaddition reactions. Predict the major stereochemical and regiochemical outcomes as appropriate. Only one of an enantiomeric pair needs to be shown.
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This note was uploaded on 02/23/2010 for the course BIO 172 taught by Professor Clark during the Winter '08 term at University of Michigan.

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Exam1Key - Name _ W.09.215H Ex a m N o . 1 Page 1 1. The...

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