Problema 20 Antitussive “narcotine” (-)-α

Problema 20 Antitussive “narcotine” (-)-α

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Problema 20
Antitussive “narcotine”
(-)-α-Noscapine is an alkaloid isolated from Papaver somniferum L. in 1817 by P. Robiquet which
named this compound as “narcotine”. This agent demonstrates significant painkilling and antitussive
activities. It is also used for treatment of cancer, stroke, anxiety, and so on. There are some syntheses
of (±)-α-noscapine. One of them is given in the scheme below.
Write down the structural formulae of compounds A–I if G is a tricyclic compound.
OMe
1)
O
O HC(OMe)3 A 1) n-BuLi
B
2) I2
MeOH
O
O
H
MeO O
H3 O+
C
DMF C11H14O 5
60-70 ° C
OMe
E
2) NaBH4
1) CH 2O
MeO
2) NaBH4
O
MeO
Br
I2
I
O
NaBH4
H
AcOK
Zn, MeCN
G
20% HCl
F
CF3CO2H
C12H15NO 4
C12H14INO3
MeO
H 2N
D
O
N
Me
H
O
NaOMe
CuI
OMe
(±)-α-noscapine
Soluzione:
O
OMe
MeO
H
C
O
OMe
O
O
O
OMe 1) BuLi
O
CH3OH
OMe
OMe
O
DMF
70°C
B
OMe
OMe
O
OMe
O
O
H3O+
H 1) H2N
O
OMe
O
OMe
N 1) CH2O
O
2) NaBH4
2) NaBH4
MeO
C
OMe
E
OMe
D
OMe
Me
O
N
20% HCl
O
Me
O
N
O
MeO
F
O
MeO
I
OMe
O
O
Br
N
O
AcOK
O
Me MeO
O
I2
H
MeO
OMe
N
O
OH
G
OMe
Me
O
NaBH4
CF3COOH
OMe
MeONa
CuI
O
2) I2
A
OMe
OMe
I
OMe
Zn, CH3CN
OMe
O
H
H
Me
(+ -)-α-noscapine
N
O
I
Soluzione proposta da Mauro Tonellato - ITI Marconi - Padova
47 IChO 2015
Baku – Azerbaijan
Soluzioni preliminari dei problemi preparatori
1