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Jeewoo Lim 2-1
2: Reactions to Know
1. Addition to Alkenes
- Alkyl halide formation
H
HX
X
X = Br, Cl, or I.
Halogen ends up on the more substituted carbon (Markovnikov Addition).
- Alcohol formation: Markovnikov
OH
1. Hg(OAc) 2
(Oxymercuration)
2. NaBH 4,
OH­
H
- Alcohol formation: anti-Markovnikov
H
1. BH 3
(Hydroboration)
2. H 2O 2,
OH ­ OH
- 1,2-Glycol formation (dihydroxylation): syn addition
1. OsO 4
HO
OH
2. H 2O,
Na2 SO3
(anti addition could be achieved through: 1) epoxide formation, followed by 2) epoxide ring opening.)
- Alkane formation (reduction of double bond)
H 2, Pd/C
H
H
(syn addition: both H atoms add from
the same face of the alkene)
or H 2 /Pt
- Bromo(and chloro) ether formation
X2
RO
(anti addition. X=Br or Cl)
ROH
X
2. Reduction of Alkynes
- cis-Alkene formation
H2
H
H
(cis product formed)
Lindlar catalyst
- trans-Alkene formation
Na
NH 3
H
(cis product f ormed)
H
Jeewoo Lim 2-2
3. Cleavage of Double Bonds
- aldehyde formation
R
R
1. O3
H
H
2. (CH 3)2S
R
2
O
H
(reductive conditions)
- ketone formation
R
R
R
R
1. O3
R
2
O
R
2. Zn/CH 3COOH
(reductive conditions)
- carboxylic acid formation
R
R
H
H
1. O 3
R
2
O
HO
2. H2O2, NaOH
(oxidative conditions)
4. C-C Bond Formation
- Wittig Reaction
R
(Ph) 3P=CR' 2
O
R
R
CR'2
("reverse" of ozonolysis)
R
- Grignard Reaction
R
R
1. R'MgX
O
R'
2. H2 O
R
OH
(f orms alcohols f rom ketones/aldehydes)
R
- Alkynylation
R
H
strong base
R
M
Base-H
(strong base: nBuLi, NaNH2, and etc. M=Li or Na, respectively.)
R
R'
(L=leaving group)
L
R
R'
L
Jeewoo Lim 2-3
5. Oxidation
- carboxylic acid formation
R
Na 2CrO 4
O
H3 O+
H
OH
H
H
O
HO
(aldehyde)
R
R
(carboxylic acid)
Na2 CrO4
H 3O+
R
O
HO
(primary alcohol)
(carboxylic acid)
- ketone/aldehyde formation
OH
R
R'
Na 2CrO 4
H3 O+
H
(secondary alcohol)
R
OH
PCC
H H
(primary alcohol)
R
O
R'
(ketone)
R
O
H
(aldehyde)
(PCC=pyridinium chlorochromate)
6. Reduction
- alcohol formation
R
LiAlH 4
O
R'O
R
R
LiAlH4
O
OH
R'
LiAlH 4
R
O
H
7. Functional Group Conversion
- conversion of -OH into a better leaving group
PBr3
Br
R
OH
TsCl
Cl
R
SOCl2
OTs
R
R
O
S
O
(Ts)