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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
"-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”)
..-CO;CH3 m, "M3
Provide mechanisms for the following tandem reactions (sequential pericyclic reactions)
a] Mob/Me I
“I H 0m 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 .
\r s ‘7‘
“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.
- Spring '09