Diproqualone
Diproqualone is a quinazolinone class GABAergic and is an analogue of methaqualone developed in the late 1950s by a team at Nogentaise de Produits Chimique. It was marketed primarily in France and some other European countries. It has sedative, anxiolytic, antihistamine and analgesic properties, resulting from its agonist activity at the β subtype of the GABAa receptor, antagonist activity at all histamine receptors, inhibition of the
cyclooxygenase-1 enzyme, and possibly its agonist activity at both the sigma-1 receptor and sigma-2 receptor (the function of these receptors and their clinical relevance has not yet been determined). Diproqualone is used primarily for treating inflammatory pain associated with osteoarthritis and rheumatoid arthritis and more rarely, for treating insomnia, anxiety and neuralgia. Diproqualone is the only analogue of methaqualone that is still in widespread clinical use, due to its useful anti-inflammatory and analgesic effects in addition to the sedative and anxiolytic actions common to other drugs of this class. There are still some concerns about the potential of diproqualone for abuse and overdose. So, it is not sold as a pure drug but only as the camphosulfonate salt in combination mixtures with other medicines such as ethenzamide. Synthesis

The reaction between isatoic anhydride [118-48-9] (1) and triethyl orthoacetate [78-39-7] in the presence of ammonium acetate provides 2-methyl-4-quinazolone [1769-24-0] (2). Alkylation of the lactone nitrogen with glycidol [556-52-5] (4) affords diproqualone (5). See also 
 Methaqualone
 Afloqualone
 Etaqualone
 Methylmethaqualone
 Mecloqualone
 Mebroqualone
 Cloroqualone
 Gamma-Aminobutyric acid

References 

Sedatives
Analgesics
Diols
Quinazolinones
GABAA receptor positive allosteric modulators
Lactams