Download Weekly Review Lecture

Review 4 Weekly Review Lecture Chem S‐20ab Reactions you learned this week:
1) Electrophilic aromatic substitution
a. Adding -Br or -Cl
b. Adding -NO2
c. Adding -SO3H
d. Friedel-Crafts acylation
e. Friedel-Crafts alkylation (used for tert-butyl or isopropyl only!)
2) Nucleophilic aromatic substitution
a. Addition-Elimination (through EWG-stabilized anionic intermediate)  used to add –OR or –SR
group
b. Elimination-Addition (through benzyne intermediate)  used to add –NH2 group
3) Reactions of aldehydes and ketones
a. NaBH4 reduction of aldehyde or ketone (revisited)
b. LiAlH4 reduction
c. Grignard or alkyl lithium addition
d. Aldehyde oxidation to carboxylic acid
e. Cyanohydrin formation
f. [Hydrate and/or hemiacetal formation] (generally not synthetically useful)
g. Acetal formation
h. Imine formation
i. Enamine formation
j. Clemmensen reduction
k. Wolff-Kishner reduction
l. Thioacetal reduction
m. Wittig alkene synthesis
n. Baeyer-Villiger oxidation
4) Returning to aldehyde or ketone
a. Acetal hydrolysis
b. Imine hydrolysis
5) Grignard + CO2
6) Reactions of carboxylic acids
a. Fischer esterification
b. Diazomethane esterification
c. Deprotonation with K2CO3 and esterification with methyl, primary, or benzyllic halides
d. SN1 tert-butyl esterification
e. SOCl2
f. LAH reduction
g. Addition of two equivalents of organolithium reagent
7) Reactions of esters
a. Transesterification
b. Acid-catalyzed hydrolysis (not as effective as base catalyzed)
c. Base-catalyzed hydrolysis (saponification)
d. Dry acid hydrolysis of tert-butyl esters
e. LAH reduction to make primary alcohol
f. (single) Reduction with DIBAL to make aldehyde
g. (double) Addition of Grignard
Review 4 Weekly Review Lecture 8) Reactions of acid chlorides
a. With water
b. With alcohol
c. With amines
d. With RZnBr or R2CuLi
9) Reactions of amides
a. Hydrolysis
b. LAH reduction
c. Dehydration to nitrile using P2O5
10) Reactions of Weinreb amides
a. (single) Grignard addition
b. LAH reduction to produce aldehyde
11) Reactions of nitriles
a. Hydrolysis
b. Reduction with LiAlH4
Chem S‐20ab Problems Part I: Explaining stuff based on aromaticity:
1) Is each of the compounds below aromatic, antiaromatic, or non-aromatic?
2) When each of the following compounds is treated with a very strong base, a specific carbanion is formed
selectively. In each case choose which of the two products would be formed and explain why.
Base
or
3) Explain the following observation. Although most hydrocarbons are fairly nonpolar, the following
hydrocarbon has a significant dipole moment. (As part of your explanation, please indicate the direction
of the dipole moment: which end is positive and which end is negative?)
Review 4 Weekly Review Lecture Part II: Aromatic Mechanisms
4) Provide a complete curved arrow mechanism for the following transformation.
Chem S‐20ab 5) Provide a mechanism for both reactions below and predict the product for the second reaction.
Part III: Aromatic Synthesis
6) Predict the major organic product for each of the following reactions.
7) Design a synthesis of the molecules below using benzene and any other reagents with four or fewer
carbon atoms.
Review 4 Weekly Review Lecture Part IV: Carbonyl Mechanisms
8) Provide a curved-arrow mechanism for the following transformations.
a.
Chem S‐20ab O
O
NaBH4
O
O
HCl, THF (0 °C)
O
b.
c.
O
EtO
EtOH
OEt
OEt
O
+
+
H + cat
EtO
OEt
(triethyl
orthoformate)
H
OEt
d.
O
O
1. PhMgBr
Me
N
Me
H
H + HNMe
2
2. H+ workup
9) Provide a complete curved-arrow mechanism for the following multistep transformation. Start by
deducing the structure of Compound A – this will help you “fill in the blanks” of the mechanism.
O
MeO
O
1. PPh 3
1.
2. nBuLi
2. H3 O+
Cl
H
Compound A
10) Phosgene, shown below, reacts with -amino acids to form carboxylic acid derivatives called
oxazolidinediones. In nonpolar solvents, two equivalents of gaseous HCl are evolved as by-product.
Provide a complete curved-arrow mechanism for this transformation.
O
O
O
OH
NH 2
Cl
Cl
(phosgene)
HN
O
+ 2 HCl
O
Part V: Carbonyl Synthesis
11) Identify the starting materials and reagents necessary to form each of the following.
EtO
OEt
O
O
O
O
O
O
Review 4 Weekly Review Lecture 12) Provide the missing starting materials or products in the following reactions.
a.
b.
c.
d.
O
OH
NaOEt
13) Provide complete syntheses for the following transformations:
a.
O
O
H
b.
c.
d.
e.
Cl
Chem S‐20ab Review 4 Weekly Review Lecture Chem S‐20ab f.
O
CN
N
g.
h.
O
O
O
O
HO
i.
j.
k.
OH
O
OH
2-indanone
m.
o.
n.
CHO
OH