Think backward

1
Synthesis and interconversions of organic
compounds
Think backward Target molecule ? Precursors

• Feasible way or not?
• Minimal number of steps
• Starting materials must be available
• Minimal time needed

2
Synthesis and interconversions of organic
compounds
Oxidation KMnO4/OH-, cold KMnO4/OH-,
heat K2Cr2O7/H3O, heat Ag(NH3)2, H2O Cu2/NaOH,
H2O, warm 1. O3, CH3CCl3 2. Zn/H2O

• Reduction
• H2, Ni
• LiAlH4/dry ether 2. H3O
• NaBH4, H2O
• HCl / Sn

Substitution and Addition Nu-, HX, X2
(Friedel-Craft alkylation) HNO3/H2SO4, RCl/AlCl3
Elimination (for R-X) Alc. KOH
Chain Lengthening KCN, Br2/NaOH/heat, I2/NaOH/heat
3
Synthesis and interconversions of organic
compounds
R NH2
RCOOH
C C
C O
R X
R OH
4
Synthesis and interconversions of organic
compounds
CH2CH2
CH3 CH2NH2



5
Synthesis and interconversions of organic
compounds
CH2CH2
CH3 CH2NH2


HCl
NH3

CH3CH2Cl
Suggested solutions The other possible ways are
welcome.
6
Synthesis and interconversions of organic
compounds
CH2CH2
CH3COOH



7
Synthesis and interconversions of organic
compounds
CH2CH2
CH3COOH
H2SO4 , heat


KMnO4/H3O reflux

CH3CH2OH
Suggested solutions The other possible ways are
welcome.
8
Synthesis and interconversions of organic
compounds
CH2CH2
CH3COH



9
Synthesis and interconversions of organic
compounds
CH2CH2
CH3COH
H2SO4 , heat

K2Cr2O7/H3O warm


CH3CH2OH
Suggested solutions The other possible ways are
welcome.
10
Synthesis and interconversions of organic
compounds
CH2CH2
CH3 CH2 COOH



11
Synthesis and interconversions of organic
compounds
CH2CH2
CH3 CH2 COOH


KCN, HCl
H3O , heat

CH3CH2CN
Suggested solutions The other possible ways are
welcome.