الفهرس 
1. Primary synthesis of phthalazine derivativesOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
Abstract
T his thesis describes the studying synthesis of new phthalazine derivatives
through the reaction of nucleophiles a with the key intermediates with the
aim to evaluate their antimicrobial activities.
The thesis consists of the following parts:
1) Summary 2) Introduction: In this section brief literatures review of the
different methods of preparation and the reactions as well as the biological
application of phthalazine derivatives.
3) Results and Discussion: It deals with the discussion of the experimental
methods adopted for the synthesis of the designed compounds as well as the
different analytical methods applied for the characterization of the new
compounds.
Scheme 1: i) AlCl3 (6h at 80 °C. ii) NH2NH2.2H2O,dry EtOH), reflux for 2h at 70 °C.
Schemes 1 illustrate the synthetic pathways followed in the preparation of
target compounds. In this part the authors synthesis 2-(4-methylbenzoyl)
benzoic acid 3 by the reaction of toluene with phthalic anhydride under Friedel
Craft’s condition. Condensation of benzoic acid derivative with hydrazine
hydrate in boiling ethanol afforded the target compound 4-(4-methylphenyl)-
2H-phthalazin-1-one 4.
1- Chlorination of compound 4.
Scheme 2: iii) POCl3, DMF, Acetonitrile.
The key intermediates p-chlorophthalazine 5 derivative was obtained upon
reaction of 4 with phosphorus oxychloride to give the corresponding 5 with
large chemical diversity on the heteroaromatic nucleus, good yield, short
reaction time and high degree of purity. The key intermediate 1-chloro-4-
tolylphthalazine 5 was used for the diversification of the phthalazine core at the
C-4 position. Thus, the phthalazine derivatives with C4-amine side chains and
different carbon spacers between the two nitrogen were synthesized after
reaction of the key intermediates, 5 with excess of appropriate amines, through a
nucleophilic aromatic substitution reaction with release of chloride at C-4 of the
aromatic nucleus of phthalazine. Therefore the key intermediate was subjected
to the following nucleophilic substitution reactions:
2. Reaction with amine derivatives:
Chloro phthalazine compound 5 was treated with amine derivatives to afford the
corresponding arylaminophthalazine 7a-f in good yields according to Scheme 3.
N
NH
O
N
N
Cl
CH3 CH3
Scheme 3: i) Et3N/CHCl3/ reflux for 2h at 60-70 °C for (7a-d). i) Et3N/DMF,
reflux for 48h at120 °C for (7e, f).
3. Reaction 1-chloro-4-tolylphthalazine 5 with various nitrogen containing
nucleophiles:
4-chlorophthalazine 5 was substituted via SNAr in DMF with an appropriate N
containing nucleophilic reagents such as amines, amino acids and
semicarbazide (cf.Scheme 5) at high temperature in presence of triethylamine,
yielding target compounds,
N
N
Cl
CH3
NH2
R2
R1
N
N
HN
CH3
R1
R2
5 7
6a=R1=R2=H
6b=R1=Cl ,R2=H
6C=R1=CF3 ,R2=H
6d=R1=OCH3 ,R2=H
6e=R1=H ,R2=COOH
6f=R1=H ,R2=NH2
i)
7=7a-7f
6
Scheme 5: i) Et3N /DMF , reflux for 48h at 135-155°C
4. Reaction 4-chlorophthalazine 5 with piprazine compound.
Scheme 6: i) Et3N /DMF, reflux for 48h at 135-155°C
N
N
Cl
CH3
R3-NH2
i)
NH
CH3
5 9
8a=R3=(CH2)3NH2
8b=R3=CH3
8c =R3= -CHCOOH
8d =R3= -CH-NHNH2
O
CH3
8e= R3=CH2COOH
R3
9a-9e
8
N
N
Cl
CH3
N
N
H
CH3
i)
N
N
N
N
CH3
CH3
5 11
10
5. Behavior of 1-chloro-4-tolylphthalazine 5 towards sulfur and oxygen
nucleophiles:
To get a new series of expected biologically active sulfur and oxygen containing
group, it was interest to react 5 with different aromatic thiols namely chloro
substituted thiols in ethanol and in presence of triethylamine, to give the
corresponding sulfur containing products 12a-c in good yields. On the other
hand 1-chloro-4-tolylphthalazine 5 reacted with phenols such as beta-napthol to
afford the corresponding oxygen containing phthalazine derivative 14 in good
yield as depicted in Scheme 4.
Scheme 4: i) Et3N /EtOH , reflux for 2 h at 80°C
The structures of all synthesized compounds were characterized by various
spectral techniques (cf. the experimental part). All the obtained spectroscopic
data was found consistent with the proposed structures of the synthesized
compounds.
Evaluation of antibacterial activity:
In this investigation,all synthesized 4-phthalazine derivatives were screened for
antibacterial activity together with the starting material 5. The antibacterial
activities of the synthesized compoundswere tested against Escherichia coli
NRRL B-210 and Pseudomonas NRRL B-23 (Gram -ve bacteria),
N
N
Cl
N
N
S
R5
R6
R4
N
N
O
CH3
CH CH3 3
R5
SH
R6
R4
OH i)
i)
5 12
13
14
11a=R4=Cl/R5,R6=H
11b=R4=CH3/R5,R6=H
11c=R4=R5=R6=H
13=B-naphthol
11
Bacillussubtilis NRRL B-543 and Staphylococcus aureus NRRL B-313 (Gram
+ve bacteria) using nutrient agar medium. Theantifungal activity of these
compounds was also testedagainst Candida albicans NRRL Y-477 using
Sabourauddextrose agar medium. Agar Diffusion. The synthesizedcompounds
were screened in vitro for their antimicrobialactivity against, by agar diffusion
method). 0.5 ml suspension of each of the aforementioned dmicroorganisms was
added to sterile nutrient agar media at 45°C and the mixture was transferred to
sterile Petri dishes and allowed to solidify. Holes of 0.9cm in diameter were
made using a cork borer. Amounts of 0.1ml of the synthesized compounds were
poured inside the holes. A hole filled with DMSO was also used as control. The
plates were left for 1 hour at room temperature as a period of pre-incubation
diffusion to minimize the effects to variation in time between the applications of
the different solutions. The diameters of the inhibition zone of were measured
and compared with that of the standard and the values were tabulated. The same
method was carried out using Sabouraud dextrose agar medium on using
Candida albicans NRRL Y-477. The plates were then incubated at 30°C for 24
hours and observed for antibacterial activity. The diameters of inhibition zone
were measured and compared with that of the standard, the values were
tabulated. Ciprofloxacin (50 μg/ml) and Fusidic acid (50 μg/ml) were used a
standard for antibacterial and antifungal activity respectively. The obtained
inhibition zones revealed that the introduction of the amino- and sulfur-side
chains at position 4 of the phthalazine nucleus resulted in a substantial increase
of the antibacterial activity in vitro against the all bacterial strains used in this
study.