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