Benzylbutylbarbiturate (5-benzyl-5-n-butylbarbituric acid) is a rare example of a barbiturate designer drug, possibly the only such compound encountered in recent years.
It was confiscated by police in Japan in 2000, and presumably was a product of clandestine manufacture as this compound has never previously been sold as a legal pharmaceutical. As with all designer drugs, this compound was produced in an attempt to circumvent drug laws prohibiting the use of most known barbiturate drugs; however, as the drug laws in many jurisdictions (including Japan) prohibit "any 5,5-disubstituted derivative of barbituric acid", this compound was deemed to be already illegal, despite being a novel compound which had not previously been encountered.[1]
This compound was known from the scientific literature and so was not a new chemical entity.[2]