Nucleophilic subistitution

1
Nucleophilic subistitution
Should take place at position ( 1 ) in agreement
with the p electron density calculation .
2
Synthesis of isoquinoline 1 Bischler
Napieralski synthesis Acyle derivatives of ß
phenyl ethylamine are cyclised by treatment
with acids after ( P2O5) to yield
dihydroisoquinoline ,which can then be aromatized
as shown .

3
NH
4
Pictet and Gams synthesis
Pictet and spengler synthesis
5
Mechanism
6
Pomeranz and Fritsch synthesis
Start from aromatic aldehyde converted into shift
base with aminoacetal followed by cyclization
gives isoquinoline .
7
Mechanism
8
Quinolizine Although a number of alkaloide are
complex derivative of Quinolizine, some time
called pyridocoline , the parent compound has
attracted attention only in recent year
9
Synthesis
10
Properties
All efforts to prepare Hquinolizine which can be
written in three structure have been unsuccessful
although complex derivatives of both 4H and 9aH
Quinolizine are well known
11
Reduction

Ring opening
12
Benzopyrylium salt and Benzopyrones
Many compounds belonging to these classes are
found in plant kingdom .Most red and blue flowers
petals contain anthocyanins ,derivatives of
benzopyrylium cation ( 1 ) ,as the coloured
material , and the yellow benzo 2 (2) and 4
pyrones ( 3 ) are also widely distributed
. Reduction product of these compound
,which can be treated as derivatives of
benzopyran ( 4 ) are also common plant
constituents .
13
The anthocyanine
The anthocyanine is hydroxylated derivatives of
the benzopyrylium cation e.g. Pelargonidin ( 5 )
and cyanidin ( 6 )
14
Ring synthesis of benzopyrylium
From phenols and 1,3 dicarbonyl compounds
15
Mechanism
16
Benzo 2 pyrones
Benzo 2 pyrone commonly called coumarin , is
the sweet smelling constituents of white clover
.A considerable number of hydroxy and methoxy
coumarins , and their glucosides , have been
isolated from plant sources .
17
Synthesis of coumarin
Coumarin can be synthesized from salicylaldehyde
by a Perkin reaction
Mechanism
18
(No Transcript)
19
(No Transcript)
20
Benzo 4 pyrones .
Benzo 4 pyrones or chromones has not yet been
isolated from natural sources , although a few
hydroxyl derivative occure in certain plant .In
contrast many 2 phenyl Benzo 4 pyrones
usually called flavones and their glycosides and
a considerable number of isoflavones have been
identified in plant extracts
21
Synthesis
2 Hydroxy acetophenone with benzaldehyde and
basic catalyst gives the unsaturated ketone ( 1)
cyclization with acid gives flavone