**6. Conclusion**

*Quinazolinone and Quinazoline Derivatives*

**4.6 Action of phosphorous sulphide**

4(3*H*)-thiones **71** [59] (**Figure 36**).

**5. Biological properties**

Treating of 4(3*H*)-quinazolinone derivatives **24** with P2S5 or phosphorus decasulfide in pyridine afforded the corresponding 2-methyl-3-aryl-quinazoline-

Quinazoline is the building stone for many naturally occurring alkaloids [60]. Many 4(3*H*)-quinazolinone derivatives represent an important category among heterocyclic compounds of medicinal interest. Other derivatives of 4(3*H*)-

quinazolinones possess a wide range of biological activities especially on the central nervous system. Moreover, other quinazoline derivatives have been reported for

Structure modification of folic acid led to the discovery of a number of antifolates as efficient anticancer agents. For example, Raltitrexed has been registered for the treatment of cancer [61]. Many quinazolinone derivatives with side chains have been reported to exhibit significant inhibitory activity against tumor cells [62]. The 2-substituted mercapto-4(3*H*)-quinazolinone bearing 6-iodo and 2-heteroarylthio

The designation of the sedative hypnotic activity of 4(3*H*)-quinazolinones led to the discovery of methaqualone as nonbarbiturate hypnotic agent. In 1965, methaqualone was introduced as sleeping pills (nonaddictive, nonbarbiturate) under the trade name Quaalude. Due to the abuse of methaqualone, it is banned in most

The search for new antiepileptic drugs with reduced toxicity and lower sideeffects is continuous. 4(3*H*)-Quinazolinone represents a very good nucleus for preparation of some new sedative/hypnotic and anticonvulsant agents, since such a heterocyclic system possesses the pharmacophoric moiety. From the literature survey, it was found that the 3*H*-quinazolin-4-one has been reported to possess different pharmacological effects, namely, sedative-hypnotic and anticonvulsant

their broad-spectrum biological activities as herein illustrated.

**5.2 4(3***H***)-Quinazolinone derivatives as sedative hypnotic agents**

**5.3 4(3***H***)-Quinazolinone derivatives as anticonvulsant agents**

**5.1 4(3***H***)-Quinazolinone derivatives as antitumour**

is identified as active anticancer agent [63].

*Synthesis of 2-methyl-3-aryl-quinazoline-4(3*H*)-thiones 71.*

countries [64].

ones [65].

**68**

**Figure 36.**

A large number of compounds which contain quinazoline moiety are known in medicinal chemistry as important compounds for their therapeutic value. Recently, there has been an increased interest in the chemistry of 4(3H)-quinazolinone system. Many derivatives of this system showed analgesic, anti-inflammatory, antiulcer, anticonvulsant, antibacterial, antifungal, anticancer and antiproliferative activities. The most common approaches to synthesize 3,2-disubstituted-4(3H)-quinazolinone derivatives involve the following steps: the amidation of 2-aminobenzoic acid derivatives and treatment of amidated anthranilic acid derivatives with acetic anhydride (or acid chloride) to afford the benzoxazinone, followed by their condensation with nitrogen nucleophiles.

## **Author details**

Samir Y. Abbas Organometallic and Organometalloid Chemistry Department, National Research Centre, Cairo, Egypt

\*Address all correspondence to: samiryoussef98@yahoo.com

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