Title: Ethers, Sulfides and Epoxides
1Ethers, Sulfides and Epoxides
chapter 11
- Structure, nomenclature, properties
- Ether synthesis - Williamson synthesis (SN2)
- H/ROH addition to olefins (chapt 6)
- Reactions - acid catalyzed cleavage of ethers
(SN2/SN1/E1) - oxidation out
- Ethers as Protecting Groups (Gps).
- Epoxides - oxirane nomenclature
- Preparation epoxidation, halohydrin
- Reactions - nucleophilic cleavage (SN2/SN1/E1)
- sulfides out
- Synthesis (continued)
blue - repeat of earlier chemistry
ss12 19
2sources nomenclature properties reactions
substitution protecting groups epoxides epoxide
reaction
3Ethers, Sulfides and Epoxides - 11
Structure - tetrahedral (sp3) oxygen carbon
4Ethers, Sulfides and Epoxides - 11
Nomenclature - ether group is a substituent
2-cyclopentenol
4-ethoxy-2-cyclopentenol
(1S,4R)-4-ethoxy-2-cyclopenten-1-ol
5Ethers, Sulfides and Epoxides - 11
Properties - polar C-O covalent bonds But low
dielectric constant
6Ethers, Sulfides and Epoxides - 11
Two ways to prep benzyl ethyl ether
Williamson ether synthesis SN2 substitution
recall similar problems in chapter 9 (9.46, 9.48
and 9.49)
7Ethers, Sulfides and Epoxides - 11
Two ways benzyl ethyl ether can be prepared
Specifically how would each be done? Nucleophic
form of the alcohol? Solvent?
- alkoxide - polar - aprotic - benzylic substrate
Which way should be best? Others? SN1, some cases
8Ethers, Sulfides and Epoxides - 11
H/ROH addition to olefins, hydration-like
Familiar?
Recall/review addition problems 6.29, 6.34a
9Ethers, Sulfides and Epoxides - 11
- Reactions - acid catalyzed cleavage of ethers
10sources nomenclature properties reactions
substitution protecting groups epoxides epoxide
reaction
11Ethers, Sulfides and Epoxides - 11
Ethers Protecting Groups (ref. problems 6.33)
Problem 6.33 alcohol interferes with Br2
addition
12Ethers, Sulfides and Epoxides - 11
Ether Protecting Groups (ref. problems 6.33)
3
1
2
Problem 6.33 alcohol interferes with Br2
addition
protecting group (Pg) blocking group
13Ethers, Sulfides and Epoxides - 11
Protecting groups characteristics
3
1
- On efficient
- Inert to rx
- Off efficient
2
Problem 6.33 alcohol interfers with Br2
addition.
protecting group (Pg) blocking group
14Ethers, Sulfides and Epoxides - 11
TMS ethers
15Ethers, Sulfides and Epoxides - 11
16Crown Ethers - not covered
- Cyclic polyethers
- The parent name is crown, preceded by a number
describing the size of the ring followed by the
number of oxygen atoms in the ring, e.g - 18-crown-6
O
O
O
O
O
O
17Ethers, Sulfides and Epoxides - 11
Nomenclature - epoxy (substituent) or oxirane
ether
4,5-epoxycycloheptene
(4S,5R)-4,5-epoxycycloheptene
18Ethers, Sulfides and Epoxides - 11
Prep of epoxides/oxiranes
19Ethers, Sulfides and Epoxides - 11
Prep of epoxides - better mechanistic view
stereospecific like bromine addition
20other epoxide sources - halohydrins/base
mechanism
intramolecular SN2
See problem 9.50, same reaction
21Other sources of epoxides - halohydrins/base
chapter 6
22Reactions of epoxides H or LA Opening
B or LB Opening
23Reactions of epoxides H or LA Opening
mechanism?
24Reactions of epoxides B or LB Opening
mechanism?
25Stereochemistry
1,2-transdiol
26Regioselectivity
SN2 like
27Regioselectivity
SN1 like
28Regioselectivity
29example epoxyresin
30Application of Epoxy Chemistry
31Application of Epoxy Chemistry
32Application of Epoxy Chemistry
33Application of Epoxy Chemistry
34Application of Epoxy Chemistry
35(No Transcript)
36lithium aluminum hydride
37Organometallic Compounds (R-M)
Organomagnesium Organolithium compds 15.1
Lithium Diorganocopper (Gilman) Reagents 15.2
Not covered Organopalladium reagents, Heck
reaction, carbenes, carbenoids, alkene
metathesis.
Synthesis, Concepts and the Final