Organic Synthesis 1, 2 – Difunctionalised Compound 1 Two Group disconnections: 1, 2 – Difunctionalised Compound. 2 Method using acyl anion equivalents. 3 Methods from alkenes. 4 Strategy of available starting material.

1. Govt: Post Graduate College Mardan 23200 KP Pakistan
Amirhassan741@gmail.com https://www.slideshare.net/amirhassan27
Name Amir Hassan
Department BS- Chemistry
Institute GPGC–Mardan KP Pakistan.
Subject Organic Synthesis
Topic 1, 2 – Difunctionalised Compound
Contents study
1 Two Group disconnections: 1, 2 – Difunctionalised Compound.
2 Method using acyl anion equivalents.
3 Methods from alkenes.
4 Strategy of available starting material.

2. Two Group Disconnection: 1, 2 – Difunctionalised compound
Written By: AMIR HASSAN CHEMISTRY DEPARTMENT GPGC MARDAN
Two Group disconnections: 1, 2 – Difunctionalised Compound.
 There are no grand unifying strategy to make 1, 2 disubstituted compound.
 There are many diverse methods which is important to judge each case on its merits.
 One common theme is a preference for disconnection (1) of bond joining the substituted
atoms.
 The nature of the problem is now revealed we have many candidates for synthons (3) the
most obvious being an aldehyde (Y=OH).
 But what of synthons (2)? This synthons has unnatural polarity (illogical) and usual
strategy will be to device a reagent for synthons (2) or, to avoid it altogether by some
alternative strategy.
The Three different diverse methods are the following :
1. Method using acyl anion equivalents.
2. Methods from alkenes.
3. Strategy of available starting material.

3. Two Group Disconnection: 1, 2 – Difunctionalised compound
Written By: AMIR HASSAN CHEMISTRY DEPARTMENT GPGC MARDAN
1. Method using acyl anion equivalents.
Disconnection of α – hydroxy ketone such as (1) require acyl anion (2) equivalents. The
acetylated ion is satisfactory here adduct (3) being hydrated to target – molecule (1) with Hg (II)
as catalyst.
Analysis:
Synthesis:
2. Methods from alkenes.
Alkenes are easily made have adjacent functionalized atom and can be converted into 1, 2
disubstituted compounds by epoxidation. Halogenations or, hydroxylation the witting reaction is
the most general approach to alkenes so the disconnection is again between the two
functionalized atoms.
(1)
(3)
(2)
(1)

4. Two Group Disconnection: 1, 2 – Difunctionalised compound
Written By: AMIR HASSAN CHEMISTRY DEPARTMENT GPGC MARDAN
α – functionalisation of carbonyl compounds:
 The synthesis of the spasmolytic – diphepanol (1) compounds an example.
 The disconnection of of one or, both phenyl group give α – amino carbonyl compounds
which can be made from the corresponding α – halo compounds.
 Halogenation of both (2) and (3) is regioselective as the the other side of carbonyl can not
easily enolise.
Diphepanol Example :

5. Two Group Disconnection: 1, 2 – Difunctionalised compound
Written By: AMIR HASSAN CHEMISTRY DEPARTMENT GPGC MARDAN
Analysis:
Synthesis:
(1)
(2)
(3)
(3)
(1)

6. Two Group Disconnection: 1, 2 – Difunctionalised compound
Written By: AMIR HASSAN CHEMISTRY DEPARTMENT GPGC MARDAN
3. Strategy of available starting material.
 Since 1, 2 disubstituted skeleton are awkward to construct one sensible strategy is to
disconnect to a readily available compounds (as in table) instead of disconnecting the 1, 2
– relationship.
 One way to disconnect diols (1) is to remove both phenyl group (Grignard) and leave
skeleton (2) of lactic acid (3).
 In the synthesis esterfication, is unnecessary as lactic acid (3) form a dimeric lactone (4)
which gives compounds (1) with Grignard reagent.

7. Two Group Disconnection: 1, 2 – Difunctionalised compound
Written By: AMIR HASSAN CHEMISTRY DEPARTMENT GPGC MARDAN
( 1 )
( 2 ) ( 3 )
( 3 ) ( 1 )
The End!!!
Thank You!!!