Summary: CHM 7200 Organic Structures and Mechanisms Fall Term 2010
Problem Set 5: This problem set is now available at (www.blackboard.wayne.edu). It will be due
in class 21 days (12/06/10) from today (11/15/10). Grades will be administered as follows: 10
(exceptional effort), 8 (complete), 5 (incomplete or inadequate effort), 2 (poor effort), 0
(nonexistent). No late problem sets will be accepted.
1. Problem: D. L. Boger et al. determined that the cyclic acetal of cyclopropenone could lead
to the ring expansion product noted below (D. L. Boger et al., J. Am. Chem. Soc., 1986, 108,
6713.). In fact, this reaction is a two-step process which involves the use of acid acid and
high temperature for completion of the final product. Please provide a mechanism that
accounts for the illustrated transformation.
2. Problem: Part A: The following multicomponent coupling cascade reaction is elegant for its
simplicity and ability to generate 6,6-fused as well as 5,6-fused ring systems. E. Karimi et al.
published this work in Tetrahedron Lett. 2008, 49,6433. Please provide A) the mechanism
for its transformation and B) provide an argument that accounts for the origin of
3. Problem: Woerpel et al. have developed an excited approach to bis-homoallylic alcohols
using carbon silanes (K. A. Woerpel et al., J. Am. Chem. Soc., 2005, 127, 2046.). The
reaction is illustrated below. Please provide a detailed mechanism for the formation of A and
then the final product itself. Please include 3D drawings to explain the chirality in the final