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R
O
RNa OH
RR
R
O
H
O
R
OH
HR
OHR
METHODS FOR THE SYNTHESIS OF ALCOHOLS (to date)
Ketones
Aldehydes
epoxides
I OH-OH
1. BH3 OH2. NaOH/H2O2
H+/H2O OH
OHOH1. OsO4
2. H2O2
OH
OH
1. mCPBA
2. H+/H2OSYN ANTI
ELECTROPHILIC AND NUCLEOPHIC CARBONMethylmagnesium bromide Methyl lithium Methyl chloride
Mg BrH3Cd- d+
LiH3Cd- d+
ClH3Cd-d+
Methyl chloride
ClH3Cd-d+
O
d+
d-
acetone
TYPICAL ELECTROPHILES
Alcohols, carbonyl compounds and carboxylic acids:REDUCTION
R C
O
OH
LiAlH4R C
O
H
R C
O
R'
NaBH4
NaBH4
R C OHH
H
R C OHH
R'
R C OHR"
R'
R C HH
H
R C HH
R'
R C HR"
R'
Primary alcohol
Secondary alcohol
Tertiary alcohol
Aldehyde
Ketone
Carboxylic acid
Reduction: Addition of H2 (or H-), loss of O or O2; loss of X2
must convert OH toleaving group
or Raney Ni/
H2
or Raney Ni/
H2
must convert OH toleaving group
Li AlH
HHH Na B
H
HHH
Lithium aluminiumhydride
Sodium borohydride
Comparison ofReducing Agents
• LiAlH4 is stronger.• LiAlH4 reduces more
stable compoundswhich are resistant toreduction. =>
Alcohols, carbonyl compounds and carboxylic acids:OXIDATION
R C HR"
R'
R C HH
R'
R C HH
H
R C OHR"
R'
R C OHH
R'
R C OHH
H
PCC
X
R C
O
R'
R C
O
H
X
PCC
NH
R C
O
OH
CrO3Cl-
Primary alcohol
Secondary alcohol
Tertiary alcohol
Aldehyde
Ketone
Carboxylic acid
Na2Cr2O7/
H2SO4
Oxidation: loss of H2, addition of O or O2, addition of X2 (halogens)
Na2Cr2O7/
H2SO4