Abstract
The preparation of series of 2-pyridyl-4(3H)-quinazolinones is described. Some of them showed a hypnotic action in mice when given orally. Studies on the structure-activity relationship demonstrated that 2-pyridyl, 3-pyridyl, and 4-pyridyl substitution at 2 position of quinazolinone ring, and o-, m-, and p-substitution of the aromatic ring at 3 position are suitable for manifestation of hypnotic activity. The order of potency of activities produced by the difference in the position of substitution of substituents at 2 and 3 position decreased in the order of 4-pyridyl, o-tolyl>3-pyridyl, o-tolyl>2-pyridyl, o-tolyl. The anthranilates of these 4(3H)-quinazolinones were inactive. A maximum hypnotic effect accompanied with other potent pharmacological properties was observed in 2-(4-pyridyl)-3-o-tolyl-4(3H)-quinazolinone (14), the potency of which was equal to or stronger than Methaqualone in mice.
