Chem112BPractice4_key - Chem H23 Spring 2007 Practice...

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Unformatted text preview: Chem H23 Spring 2007 Practice Probiems (04/20/07) Problem 1 Cycloaddition reactions are sometimes catalyzed by the addition of a Lewis acid (examples shown above arrows below). The cycloadditions may also occur in an intramolecular fashion. Provide major products for the following reactions 0" Ticl. a] + I I fig UV 0 BF OOEt \ a 2 O M t e In Heat (aim 3 W cl W + H—E—COIMQ -—I- I; / E 0.101 Problem 2 Provide products for the following sigmatropic reactions. Q? EC) H- " 60"6 ‘ bl O -—I-- Q. [4 T) H "-0 100 "C c: Q Wl’ —-* Hac‘” Problem 3 Predict the major electrocyclic products of the following transformations. "8 OCH, Heat Two dlastareomaric _—"‘ Products HO Two diastereOmeric Products b} H .nCOfiH; Heat I (\Lofilia "cozcss H L019”) H _ ..-CO;CH3 m, "M3 —I- "-cozcaa| H (.066 pl} Problem 4 Provide mechanisms for the following tandem reactions (sequential pericyclic reactions) 0H 0% M e Me a] Mob/Me I se (3 “I H 0m H _'h- m (:3 @311) H Problem 5 The ene reaction involves a 6-electron transition state that is related to that of the Diels- Alder reaction and the Claisen rearrangement. Keeping this in mind, provide an arrow- pushing mechanism for the following transformation. a t; 3 I Heat t 3W ——i‘" a 6 "l L 3“ as . ? s tt't ‘ \r s ‘7‘ 1"“) H “y H ...
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This note was uploaded on 02/22/2010 for the course CHEM N/A taught by Professor Head-gordon during the Spring '09 term at University of California, Berkeley.

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Chem112BPractice4_key - Chem H23 Spring 2007 Practice...

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