CHEM 334: Spring 2014
Recitation Section 3/20/2014
1. Provide a mechanism for the following multiple cyclization.
BF 3
OH
MeO
MeO
2. Design a synthetic plan for the following transformation
O
CO2Me
H 2N
OMe
Br
NO 2
3. Rank the compounds in each of the following groups in order of decreasing reactivity toward
electrophilic aromatic substitution. Explain your ranking.
CH 3
CCl 3
CHCl2
CH2Cl
A.
OMe
O Na
OCOMe
CH 3
CO2H
CO2H
CH 3
CO2H
CH 3
B.
CH2CH 3
CH2CCl 3
CH2CF 3
CF2CH 3
D.
C.
4. The nitroso group –NO, as a substituent on a benzene ring acts as an ortho, para- directing
group but is deacitvating. Use the Lewis structure of the nitroso group and its inductive and
resonance interactions with the benzene ring to explain this finding. (Hint: Consider possible
similarities to another type of substituent that is ortho, para-directing but deactivating.)
5. Typical conditions for nitrosation are illustrated in the following equation. Propose a detailed
mechanism for this reaction.
OH
OH
OH
NaNO 2, HCl, H 2O
NO
NO