Page 69 - Org 3 theoritical book 2024-25

Clinical Pharmacy PharmD - 2024/2025 Level 2 Pharmaceutical Organic Chemistry-3 (PC 305)

NH 2 NH 2 CH OH OH
N N 3 N N CH 3

HO N HO N HO N HO N

Cytosine 5-methylcytosine uracil thymine

They also occur in barbiturates, vit. B 1, B 12 and a number of coenzymes.
Synthesis:

O HO
NH 2 HOOC
O C CH 2 POCl 3 N O N OH
NH 2 HOOC N HO N
urea malonic acid O
barbituric acid = 2,4,6-trihydroxypyrimidine
(malonylurea)
EtOOC NaOEt
CH 2
EtOOC POCl 3

diethyl malonate Cl

N Zn/H O N
2
N Cl N Cl
pyrimidine

c) Pyrazines

Pyrazine itself may be prepared as follows:

H H
CH 2 NH 2 CH 2 N Al O / N N
O 2 3
CH 2 NH 2 CH 2 NH OH -H O N -3H 2 N
2
ethylene ethylene 2 H pyrazine
diamine oxide piperazine
(hexahydropyrazine)
d) Benzodiazines:

The important benzodiazines usually have trivial names as follows:

N
N N
N N
N N N
cinnoline phthalazine quinazoline qunoxaline
Of these diazonaphthalenes the following are of importance: