Question: In what decades was the synthetic stimulant of which Alpha-Pyrrolidinopentiothiophenone is an analogue where the phenyl ring has been replaced by thiophene developed?
Context: Thiopropamine is a stimulant drug which is an analogue of amphetamine where the phenyl ring has been replaced by thiophene.  It has similar stimulant effects to amphetamine but with around one third the potency.  The N-methyl and thiophen-3-yl analogues are also known and are somewhat more potent, though still generally weaker than the corresponding amphetamines. O-2172 is a drug developed by Organix Inc, which acts as a stimulant and potent dopamine reuptake inhibitor.  It is an analogue of methylphenidate where the phenyl ring has had a 3,4-dichloro substitution added, and the piperidine ring has been replaced by cyclopentane.  It is around 1/3 the potency of methylphenidate, demonstrating that even with the important binding group of the nitrogen lone pair removed entirely, selective DAT binding and reuptake inhibition is still possible. DOx is a chemical class of substituted amphetamine derivatives featuring methoxy groups at the 2- and 5- positions of the phenyl ring, and a substituent such as alkyl or halogen at the 4- position of the phenyl ring.  The compounds of this class are potent and long-lasting psychedelic drugs, and act as highly selective 5-HT, 5-HT, and 5-HT receptor partial agonists. Bosseopentaenoic acid (BPA) is a conjugated polyunsaturated fatty acid.  Bosseopentaenoic acid can be extracted from the red coralline algae, "Bossiella orbigniana".  The first total synthesis of methyl bosseopentaenoate by consecutive palladium-catalyzed reactions was reported in 2011.  In 2017, bosseopentaenoic acid was obtained from the ester hydrolysis of methyl bosseopentaenoate in good yield using mild condition and the synthesis of its sulfur-bridged analogue of BPA; thiophene analogue was achieved by Mohamed and Solum In this study, a comparison between the thiophene analogue and BPA with respect to their antioxidant activity was accomplished.  It was shown that the rigidified analogue; the thiophene analogue exhibited higher free radical scavenging potential than the bosseopentaenoic acid.  The results showed that by lowering the flexibility of the BPA as lead compound by incorporation thiophene ring in its structure, an increased antioxidant activity was observed.  This study opens the door to investigate the relationship between the flexibility of other polyunsaturated fatty acids (PUFAs) and enhancement in the biological activity. α-Pyrrolidinopentiophenone (also known as α-pyrrolidinovalerophenone, α-PVP, O-2387, β-keto-prolintane, Prolintanone, or Desmethyl Pyrovalerone) is a synthetic stimulant of the cathinone class developed in the 1960s that has been sold as a designer drug.  Colloquially it is sometimes called flakka or gravel.  α-PVP is chemically related to pyrovalerone and is the ketone analog of prolintane. Sufentanil (R30730, brand name Sufenta) is a synthetic opioid analgesic drug approximately 5 to 10 times more potent than its parent drug, fentanyl, and 500 times as potent as morphine.  Structurally, sufentanil differs from fentanyl through the addition of a methoxymethyl group on the piperidine ring (which is believed to reduce duration of action), and the replacement of the phenyl ring by thiophene.  Sufentanil first was synthesized at Janssen Pharmaceutica in 1974. Troparil (also known as (–)-2β-Carbomethoxy-3β-phenyltropane, WIN 35,065-2, or β-CPT) is a stimulant drug used in scientific research.  Troparil is a phenyltropane-based dopamine reuptake inhibitor (DRI) that is derived from methylecgonidine.  Troparil is a few times more potent than cocaine as a dopamine reuptake inhibitor, but is less potent as a serotonin reuptake inhibitor, and has a duration spanning a few times longer, since the phenyl ring is directly connected to the tropane ring through a non-hydrolyzable carbon-carbon bond.  The lack of an ester linkage removes the local anesthetic action from the drug, so troparil is a pure stimulant.  This change in activity also makes troparil slightly less cardiotoxic than cocaine.  The most commonly used form of troparil is the tartrate salt, but the hydrochloride and naphthalenedisulfonate salts are also available, as well as the free base. In organic chemistry, the phenyl group or phenyl ring is a cyclic group of atoms with the formula CH.  Phenyl groups are closely related to benzene and can be viewed as a benzene ring, minus a hydrogen,which may be replaced by some other element or compound to serve as a functional group.  Phenyl groups have six carbon atoms bonded together in a hexagonal planar ring, five of which are bonded to individual hydrogen atoms, with the remaining carbon bonded to a substituent.  Phenyl groups are commonplace in organic chemistry.  Although often depicted with alternating double and single bonds, phenyl groups are chemically aromatic and show nearly equal bond lengths between carbon atoms in the ring. Methylmethaqualone (MMQ) is a quinazolinone and an analogue of methaqualone that has similar sedative and hypnotic properties to its parent compound (resulting from its agonist activity at the β subtype of the GABA receptor), and is around the same potency.  Methylmethaqualone differs from methaqualone by 4-methylation on the phenyl ring.  It was made illegal in Germany in 1999 and listed by the DEA as a "drug of forensic interest" at about the same time, but little other information is available.  It would appear that this compound was sold on the black market in Germany as a designer drug analogue of methaqualone. α-Pyrrolidinopentiothiophenone (also known as α-PVT) is a synthetic stimulant of the cathinone class that has been sold online as a designer drug.  It is a analogue of α-PVP where the phenyl ring has been replaced by thiophene.
Answer: the 1960s