Problem_set_9

Problem_set_9 - non-synchronous , but still concerted...

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Problem set 9, Chem. 127/227, Fall quarter 2007 1. The Diels-Alder reaction of 1,1-dideuterio-2-methyl-1,3-butadiene (aka isoprene-1,1-d 2 ) with acrylonitrile leads to the formation of the expected regioisomeric cycloadducts. From a competition experiment using isoprene-d 0 and isoprene-1,1-d 2 , researchers (Gajewski, Peterson, Kagel, Huang, JACS , 1989 , 111 , 9078-9081) were able to determine secondary KIEs. In the formation of the 5-cyano cycloadduct, they measured k H /k D = 1/1.020, while for the 4- cyano adduct it was 1/1.13. Interpret the results insofar as they are related to the
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Unformatted text preview: non-synchronous , but still concerted nature of the Diels-Alder reaction when acrylonitrile is used as the dienophile. 2. See if you can devise what you hope might be an efficient synthesis of the isotopically labeled materials listed below. Be fully cognizant of the fact that each will be volatile; the alcohol has the added bonus of being water soluble, thereby making its isolation in a pure form a potential major headache. Good luck. (a) isoprene-4,4-d 2 (b) CH 2 =CHCD 2 OH...
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