Multimodal imaging of hallucinogens 25C‐ and 25I‐NBOMe on blotter papers

Due to the much lower production costs but similar effects to lysergic acid diethylamide (LSD), phenethylamine derivatives are sold as a cheaper replacement or deceptively as LSD itself. These potent hallucinogenic substances can lead to severe intoxication, thus a more profound understanding of their use is required. This includes the elucidation of the manufacturing processes for the commonly used blotter papers and the assessment of the risk of overdosing because of a heterogeneous distribution on the blotter papers. Besides the rapid detection of the analytes, the manufacturing process was elucidated by three different imaging techniques and liquid chromatography‐mass spectrometry (LC–MS). A blotter paper sample, containing the two hallucinogenic phenethylamine derivatives 25I‐NBOMe and 25C‐NBOMe, was analyzed by complementary techniques such as micro x‐ray fluorescence (μXRF), laser ablation (LA)‐inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), matrix assisted laser desorption ionization (MALDI)‐MS, and with LC–MS after extraction. Using the signal from chlorine and iodine within the compounds, μXRF proved to be the fastest, cheapest and easiest method for identification, requiring no sample preparation at all. LA‐ICP‐OES provided three‐dimensional information of the elements in the blotter paper. These results helped to confirm the assumption that manufacturers spray the compounds onto the paper. Whereas μXRF and LA‐ICP‐OES detected signals for chlorine and iodine, MALDI‐MS‐imaging showed the molecular distribution of both analytes. LC–MS analyses as a complementary method support the imaging results. Quantitative results for different drug hotspots revealed a heterogeneous distribution of the drugs on the blotter paper implying an inherent risk of overdosing for consumers.     

Synthesis and determination of analytical characteristics and differentiation of positional isomers in the series of N‐(2‐methoxybenzyl)‐2‐(dimethoxyphenyl)ethanamine using chromatography–mass spectrometry

N‐(2‐Methoxybenzyl)‐2,5‐dimethoxyphenethylamines (NBOMes) are synthetic phenethylamine derivatives emerging on the global drug market and reported to be associated with untoward effects in people who use drugs. Its action involves agonism at serotonin 5‐HT_2A receptors, affecting cognitive and behavioral processes. However, certain isomers of NBOMes may not show any psychoactive effects. They are not controlled by legislation and can be tested as pharmaceutical drugs. This study deals with the differentiation among positional isomers of 25H‐NBOMe differing in the position of the two methoxy groups in the phenylethyl moiety of the molecule, using chromatography–mass spectrometry methods. The gas chromatography analysis showed that the isothermal mode was more efficient than the usually applied temperature‐programming mode for the separation of the mentioned isomers. Electron ionization mass spectra of 25H‐NBOMe isomers were highly similar, often resulting in a high probability of erroneous identification. However, mass spectra of their trifluoroacetyl or pentafluoropropanoyl derivatives were easily identified as they contained fragments with many significant differences. The proposed analysis using liquid chromatography–tandem mass spectrometry could distinguish the isomers of 25H‐NBOMe without the need for any derivatization.     

Analytical characterization of four new ortho‐methoxybenzylated amphetamine‐type designer drugs

In a seizure of German custom authorities four N‐(ortho‐methoxybenzyl)amines with amphetamine partial structure were obtained as pure compounds: N‐(ortho‐methoxybenzyl)‐3,4‐dimethoxyamphetamine (3,4‐DMA‐NBOMe ( 1 )), N‐(ortho‐methoxybenzyl)‐4‐ethylamphetamine (4‐EA‐NBOMe ( 2 )), N‐(ortho‐methoxybenzyl)‐4‐methylmethamphetamine (4‐MMA‐NBOMe ( 3 )), and N‐(ortho‐methoxybenzyl)‐5‐(2‐aminopropyl)benzofuran (5‐APB‐NBOMe ( 4 )). The compounds have been detected in Germany for the first time and no analytical data had been previously published. Mass spectrometric (MS), infrared (IR) spectroscopic, and nuclear magnetic resonance (NMR) spectroscopic data are presented. Copyright © 2015 John Wiley & Sons, Ltd.     

Identification and characterization of 2,5‐dimethoxy‐3,4‐dimethyl‐β‐phenethylamine (2C‐G) – A new designer drug

This study presents and discusses the mass spectrometric, infrared spectroscopic and nuclear magnetic resonance spectroscopic data of 2,5‐dimethoxy‐3,4‐dimethyl‐β‐phenethylamine (2C‐G), a new designer drug. A powder sample containing 2C‐G was seized in Poland in 2011. The paper focuses on a comparison of the analytical features of 2C‐G and other members of the 2C‐series, in order to assess the possibility of unequivocal identification. The occurrence of intense peak at m/z = 178 and different intensities of the ions at m/z = 165 and 180 in the gas chromatography‐electron impact‐mass spectrometry (GC‐EI/MS) spectrum of 2C‐G made it possible to distinguish it from 2C‐E. Differences in relative intensities of the ions at m/z = 192, 179 and 177 were observed for GC‐EI/MS spectra of TFAA derivatives of 2C‐G and 2C‐E. An identical set of ions was recorded for these substances using the liquid chromatography‐electrospray ionization/quadrupole time of flight mass spectrometry (LC‐ESI/QTOFMS) method in both MS and tandem mass spectrometry (MS/MS) mode, but the distinction was possible based on differences in the ion intensities at m/z = 193.1223 and 178.0988. The Fourier transform infrared (FTIR) spectrum of 2C‐G was significantly different from other members of the 2C‐series, with a characteristic doublets at 993–1014 cm^‐1 and 1099–1124 cm^‐1, and the ratio of bands at higher wavenumbers. Final elucidation of the structure of 2C‐G was carried out by ¹H and ¹³C NMR spectroscopy. The study indicated that the marketing of analogues of controlled substances poses a real analytical challenge for forensic laboratories, and the application of sophisticated methods is often required for unequivocal identification of a new substance. Copyright © 2012 John Wiley & Sons, Ltd.     

13C‐ and 14C‐labelling of N‐[1‐(4‐chlorophenyl)‐1H‐pyrrol‐2‐yl‐methyleneamino] guanidinium acetate

N‐[1‐(4‐chlorophenyl)‐1H‐pyrrol‐2‐yl‐¹³C₄‐methyleneamino]guanidinium acetate has been synthesized by a four‐step procedure. This involved reduction of the Weinreb amide N,N′‐dimethyl‐N,N′‐dimethyloxybutane‐1,4‐diamide‐1,2,3,4‐¹³C₄ by Dibal‐H to give the corresponding unstable dialdehyde which is reacted in situ with 4‐chloroaniline to form 1‐(4‐chlorophenyl)‐1H‐pyrrole‐¹³C₄. This pyrrole analogue underwent a Vilsmeyer acylation with POCl₃/DMF followed by final reaction with aminoguanidine bicarbonate to produce the desired labelled compound with 99% atom ¹³C. By using DMF [α‐¹⁴C] a radio‐labelled analogue was synthesized with a specific activity of 60 mCi/mmol. Copyright © 2005 John Wiley & Sons, Ltd.     

Identification of five substituted phenethylamine derivatives 5‐MAPDB, 5‐AEDB,MDMA methylene homolog, 6‐Br‐MDMA,and 5‐APB‐NBOMe

This paper reports analytical properties of five substituted phenethylamine derivatives seized from a clandestine laboratory. These five derivatives include 5‐(2‐methylaminopropyl)‐2,3‐dihydrobenzofuran (5‐MAPDB, 1 ), 5‐(2‐aminoethyl)‐2,3‐dihydrobenzofuran (5‐AEDB, 2 ), N ,2‐dimethyl‐3‐(3,4‐methylenedioxyphenyl)propan‐1‐amine (MDMA methylene homolog, 3 ), 6‐bromo‐3,4‐methylenedioxymethamphetamine (6‐Br‐MDMA, 4 ), and 1‐(benzofuran‐5‐yl)‐N ‐(2‐methoxybenzyl)propan‐2‐amine (5‐APB‐NBOMe, 5 ). These compounds were identified by liquid chromatography‐quadrupole time‐of‐flight mass spectrometry (LC‐QTOF‐MS), gas chromatography‐mass spectrometry (GC‐MS), and nuclear magnetic resonance spectroscopy (NMR). No analytical properties about compounds 1‐4 have appeared until now, making this the first report on these compounds. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis,characterization, and antimicrobial activity of some new N‐aryl‐N’‐(2‐oxoindolin‐3‐ylidene)‐benzohydrazonamides

A green approach was developed for synthesizing a series of (isatin‐3‐ylidene)‐hydrazonamides 3a–j  from the reaction between isatin, (isatin‐3‐ylidene)malononitrile, or 2‐cyano‐2‐(2‐isatin‐3‐ylidene)acetate and benzohydrazonamide in ethyl acetate solutions at ambient temperature. The structures of the new compounds were confirmed on the basis of spectral data. In this eco‐friendly medium, a variety of (isatin‐3‐ylidene)hydrazonamides were obtained free of catalyst in good to excellent yields. All the synthesized products were evaluated for their antimicrobial activity. Among the compounds tested, 3b and 3d exhibited good antibacterial activity against Staphylococcus aureus, whereas others responded moderately with reference to the standard drug ciprofloxacin.     

N‐2‐(4‐N‐(4‐[18F]Fluorobenzamido)phenyl)‐propyl‐2‐propanesulphonamide: synthesis and radiofluorination of a putative AMPA receptor ligand

Arylpropylsulphonamides are in the focus of research as α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolpropionic acid (AMPA) receptor ligands. A new fluorine‐18‐labelled potentiator of AMPA receptors was synthesized as a potential radiotracer for cerebral imaging with positron emission tomography. Using N‐2‐(4‐N‐(4‐nitrobenzamido)phenyl)‐propyl‐2‐propanesulphonamide ( 7 ) as labelling precursor for a Kryptofix 2.2.2^®/K₂CO₃‐activated nucleophilic radiofluorination, the putative AMPA receptor ligand N‐2‐(4‐N‐(4‐[¹⁸F]fluorobenzamido)phenyl)‐propyl‐2‐propanesulphonamide [¹⁸F] 8 was obtained in one step. Optimization of the reaction parameters time, temperature, solvent and concentration gave a radiochemical yield of 38±8% at 180°C in dimethylsulphoxide within 30‐min reaction time. After a solid‐phase extraction followed by a high‐performance liquid chromatography separation, the product could be obtained in radiochemical yields of 5±1.5%. Radiochemical purity was higher than 95% and the specific activity amounted to 77±40 GBq/µmol. First in vitro assays with rat brain slices revealed a high non‐specific binding and a uniform distribution of [¹⁸F] 8 not lending it for in vivo imaging purposes. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis and characterization of N‐(2‐chloro‐5‐methylthiophenyl)‐N′‐(3‐methylthiophenyl)‐N′‐[11C]methylguanidine [11C]CNS 5161, a candidate PET tracer for functional imaging of NMDA receptors

N‐methyl‐D ‐aspartate (NMDA) receptors play a key role in excitatory neurotransmission and are linked to a variety of acute and chronic neurodegenerative diseases including epilepsy, schizophrenia, Parkinson's disease and drug abuse. N‐(2‐chloro‐5‐methylthiophenyl)‐N′‐(3‐methylthiophenyl)‐N′‐methylguanidine (CNS 5161) is a high affinity ligand (Ki=1.87±0.25 nM) for the NMDA PCP site, which potentially can be used for functional imaging of this receptor. Herein we report the synthesis of the corresponding positron emission tomography (PET) tracer [¹¹C]CNS 5161 by means of [¹¹C]methylation of the desmethyl guanidine precursor. [¹¹C]CNS 5161 was synthesized with a decay corrected radiochemical yield of 10% within 45 min after end of bombardment (EOB). The final product was prepared in a sterile saline solution suitable for clinical studies with a radiochemical purity of >96% and a specific activity of 41 GBq/mmol at time of injection. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis and Anticonvulsant Activity of New N‐(Alkyl/Sub‐stituted aryl)‐N′‐[4‐(5‐cyclohexylamino)‐1,3,4‐thiadiazole‐2‐yl)phenyl]thioureas

A series of novel thiourea derivatives carrying the 5‐cylohexylamino‐1,3,4‐thiadiazole moiety was synthesized and their anticonvulsant activity was evaluated. Structures of the synthesized compounds have been confirmed by IR, ¹H‐NMR, and elemental analysis. All of the compounds were administered at a dose of 50 mg/kg. Some of the active compounds have different effects in pentylenetetrazole (PTZ) and maximal electroshock (MES) tests, indicating the therapeutical potential in petit mal seizures, but not in grand mal seizures. Compounds 10 , 11 , 13 , and 14 carrying 2‐methylphenyl, 4‐chlorophenyl, allyl, and 4‐methylphenyl on the thiourea pharmacophore, increased the survival rate in the PTZ model. The ED₅₀ values of the active compounds 10 , 11 , 13 , and 14 were found 68.42, 43.75, 18.75 and 25 mg/kg, respectively.     

Novel probes for imaging amyloid‐β: F‐18 and C‐11 labeling of 2‐(4‐aminostyryl)benzoxazole derivatives

2‐(4‐Methylaminostyryl)‐6‐(2‐[¹⁸F]fluoroethoxy)benzoxazole ([¹⁸F]BF‐168) was prepared and found to be a potential probe for imaging amyloid‐β. The precursor, a 6‐(2‐tosyloxyethoxy)benzoxazole derivative, was fluorinated with [¹⁸F]KF and Kryptofix 222 in acetonitrile, and the crude product purified by semi‐preparative HPLC to give [¹⁸F]BF‐168. The radiochemical purity was >95% and the maximum specific activity was 106 TBq/mmol at the end of synthesis. The synthesis time was 110 min from the end of bombardment. 2‐(4‐[N‐methyl‐¹¹C]methylaminostyryl)‐5‐fluorobenzoxazole ([¹¹C]BF‐145) was also prepared from 2‐(4‐aminostyryl)‐5‐fluorobenzoxazole, [¹¹C]MeI and 5 N NaOH in DMSO, and purified by semi‐preparative HPLC. The radiochemical purity was >95% and the specific activity was 40–70 TBq/mmol at the end of synthesis. The synthesis time was 45 min from the end of bombardment. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis of N‐(2‐chloro‐5‐methylthiophenyl)‐ N′‐(3‐methyl‐thiophenyl)‐ N′‐[3H3]methylguanidine, {[3H3]CNS‐5161}

The preparation of the title compound, [³H₃]CNS‐5161, was accomplished in three steps starting with the production of [³H₃]iodomethane (CT₃I). The intermediate N‐[³H₃]methyl‐3‐(thiomethylphenyl)cyanamide was prepared in 77% yield by the addition of CT₃I to 3‐(thiomethylphenyl)cyanamide, previously treated with sodium hydride. Reaction of this tritiated intermediate with 2‐chloro‐5‐thiomethylaniline hydrochloride formed the guanidine compound [³H₃]CNS‐5161. Purification by HPLC gave the desired labeled product in an overall yield of 9% with >96% radiochemical purity and a final specific activity of 66 Ci mmol^?1. Copyright © 2002 John Wiley & Sons, Ltd.     

Cytotoxic effects of psychotropic benzofuran derivatives,N‐methyl‐5‐(2‐aminopropyl)benzofuran and its N‐demethylated derivative,on isolated rat hepatocytes

The novel psychoactive compounds derived from amphetamine have been illegally abused as recreational drugs, some of which are known to be hepatotoxic in humans and experimental animals. The cytotoxic effects and mechanisms of 5‐(2‐aminopropyl)benzofuran (5‐APB) and N‐methyl‐5‐(2‐aminopropyl)benzofuran (5‐MAPB), both of which are benzofuran analogues of amphetamine, and 3,4‐methylenedioxy‐N‐methamphetamine (MDMA) were studied in freshly isolated rat hepatocytes. 5‐MAPB caused not only concentration‐dependent (0–4.0 mm ) and time‐dependent (0–3 h) cell death accompanied by the depletion of cellular ATP and reduced glutathione and protein thiol levels, but also accumulation of oxidized glutathione. Of the other analogues examined at a concentration of 4 mm , 5‐MAPB/5‐APB‐induced cytotoxicity with the production of reactive oxygen species and loss of mitochondrial membrane potential was greater than that induced by MDMA. In isolated rat liver mitochondria, the benzofurans resulted in a greater increase in the rate of state 4 oxygen consumption than did MDMA, with a decrease in the rate of state 3 oxygen consumption. Furthermore, the benzofurans caused more of a rapid mitochondrial swelling dependent on the mitochondrial permeability transition than MDMA. 5‐MAPB at a weakly toxic level (1 mm ) was metabolized slowly: levels of 5‐MAPB and 5‐APB were approximately 0.9 mm and 50 μm , respectively, after 3 h incubation. Taken collectively, these results indicate that mitochondria are target organelles for the benzofuran analogues and MDMA, which elicit cytotoxicity through mitochondrial failure, and the onset of cytotoxicity may depend on the initial and/or residual concentrations of 5‐MAPB rather than on those of its metabolite 5‐APB. Copyright © 2016 John Wiley & Sons, Ltd.     

Scalable synthesis and antibacterial evaluation of 2‐(3‐(N‐(substituted phenyl)sulfamoyl)ureido)benzothiazoles

A new series of 2‐(3‐(N‐(substituted phenyl)sulfamoyl)ureido)benzothiazoles was synthesized via a one‐pot efficient and scalable method, involving the condensation of 2‐aminobenzothiazoles derivatives, substituted anilines, and chlorosulfonyl isocyanate. The products were obtained in good yield with a simple workup, and their structures were confirmed from their spectral analyses. The synthesized compounds were further screened for their antibacterial activity against Gram‐positive and Gram‐negative pathogenic strains. The molecules show promising activity in the MIC value range of 2–0.25 µg/ml against selected bacterial strains, especially against nonfermentative carbapenem‐resistant bacteria (Pseudo VIM‐2 and Acinetobacter baumanni).     

Analytical characterization of N,N‐diallyltryptamine (DALT) and 16 ring‐substituted derivatives

Many N ,N ‐dialkylated tryptamines show psychoactive properties in humans and the number of derivatives involved in multidisciplinary areas of research has grown over the last few decades. Whereas some derivatives form the basis of a range of medicinal products, others are predominantly encountered as recreational drugs, and in some cases, the areas of therapeutic and recreational use can overlap. In recent years, 5‐methoxy‐N ,N ‐diallyltryptamine (5‐MeO‐DALT) has appeared as a new psychoactive substance (NPS) and ‘research chemical’ whereas 4‐acetoxy‐DALT and the ring‐unsubstituted DALT have only been detected very recently. Strategies pursued in the authors' laboratories included the preparation and biological evaluation of previously unreported N ,N ‐diallyltryptamines (DALTs). This report describes the analytical characterization of 17 DALTs. Fifteen DALTs were prepared by a microwave‐accelerated Speeter and Anthony procedure following established procedures developed previously in the authors' laboratories. In addition to DALT, the substances included in this study were 2‐phenyl‐, 4‐acetoxy‐, 4‐hydroxy‐, 4,5‐ethylenedioxy‐, 5‐methyl‐, 5‐methoxy‐, 5‐methoxy‐2‐methyl‐, 5‐ethoxy‐, 5‐fluoro‐, 5‐fluoro‐2‐methyl‐, 5‐chloro‐, 5‐bromo‐, 5,6‐methylenedioxy‐, 6‐fluoro‐, 7‐methyl, and 7‐ethyl‐DALT, respectively. The DALTs were characterized by nuclear magnetic resonance spectroscopy (NMR), gas chromatography (GC) quadrupole and ion trap (EI/CI) mass spectrometry (MS), low and high mass accuracy MS/MS, photodiode array detection, and GC solid‐state infrared analysis, respectively. A comprehensive collection of spectral data was obtained that are provided to research communities who face the challenge of encountering newly emerging substances where analytical data are not available. These data are also relevant to researchers who might wish to explore the clinical and non‐clinical uses of these substances. Copyright © 2016 John Wiley & Sons, Ltd.     

Radiosynthesis of [123I]N‐(3‐iodoprop‐(2E)‐enyl)‐2α‐(imino‐methyl)‐3β‐(3′,4′‐dichlorophenyl) nortropane as a potential SPET tracer for dopamine transporter

The radiosynthesis of a novel tropane derivative [¹²³I]KUC‐25019, [[¹²³I];N‐(3‐iodoprop‐(2E)‐enyl)‐2α‐(imino‐methyl)‐3β‐(3′,4′‐dichlorophenyl)nortropane], a potential inhibitor of the dopamine transporter is reported. The synthetic routes include the preparation of standard reference, the stannyl precursor and the ¹²³I‐labeling synthesis. The no‐carrier‐added ¹²³I‐labeling has about 20% yield, the specific activity of [¹²³I]KUC‐25019 is > 107 GBq/µmol and the radiochemical purity of [¹²³I] KUC‐25019 is >95%. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis,molecular docking,and pharmacological evaluation of N‐(2‐(3,5‐dimethoxyphenyl)benzoxazole‐5‐yl)benzamide derivatives as selective COX‐2 inhibitors and anti‐inflammatory agents

A series of N‐(2‐(3,5‐dimethoxyphenyl)benzoxazole‐5‐yl)benzamide derivatives ( 3am ) was synthesized and evaluated for their in vitro inhibitory activity against COX‐1 and COX‐2. The compounds with considerable in vitro activity (IC₅₀ < 1 μM) were evaluated in vivo for their anti‐inflammatory potential by the carrageenan‐induced rat paw edema method. Out of 13 newly synthesized compounds, 3a , 3b , 3d , 3g , 3j , and 3k were found to be the most potent COX‐2 inhibitors in the in vitro enzymatic assay, with IC₅₀ values in the range of 0.06–0.71 μM. The in vivo anti‐inflammatory activity of these six compounds ( 3a , 3b , 3d , 3g , 3j , and 3k ) was assessed by the carrageenan‐induced rat paw edema method. Compounds 3d (84.09%), 3g (79.54%), and 3a (70.45%) demonstrated significant anti‐inflammatory activity compared to the standard drug ibuprofen (65.90%) and were also found to be safer than ibuprofen, by ulcerogenic studies. A docking study was done using the crystal structure of human COX‐2, to understand the binding mechanism of these inhibitors to the active site of COX‐2.

     

Synthesis of N‐methylmorpholine N‐(17O‐oxide) and N‐methylmorpholine 15N‐(17O‐oxide)

N‐Methylmorpholine N‐(¹⁷O‐oxide) and N‐methylmorpholine ¹⁵N‐(¹⁷O‐oxide) were prepared from N‐methylmorpholine and ¹⁵N‐methylmorpholine by oxidation with H₂ ¹⁷O₂. The facile one‐pot procedure provided yields of 82 and 76%, respectively. The labeled hydrogen peroxide was obtained by electrolysis of H₂ ¹⁷O followed by autoxidation of 2‐ethylanthraquinol with the molecular oxygen ¹⁷O₂ generated. The compounds serve for mechanistic studies into gold nanoparticle generation in NMMO solution. Copyright © 2009 John Wiley & Sons, Ltd.     

Optimization of labeling dipicolylamine derivative,N,N'‐(5‐(4‐aminobutoxy)‐1,3‐phenylene)bis(methylene)bis(1‐(pyridin‐2‐yl)‐N‐(pyridin‐2‐ylmethyl)methanamine), with three 18F‐prosthetic groups as potential imaging agents for metastatic infectious disease

The aim of this study was to develop ¹⁸ F‐labeled dipicolylamine derivative (compound 1) with three ¹⁸ F‐prosthetic groups, ¹⁸ F‐NFP, ¹⁸ F‐SFB, and ¹⁸ F‐FET, which were synthesized with labeling yields of 72 ± 10%, 75 ± 8%, and 90 ± 8%, respectively. Compound 1 was then conjugated with ¹⁸ F‐NFP, ¹⁸ F‐SFB, and ¹⁸ F‐FET, respectively. Factors such as the amount of 1 , reaction temperature, and time were examined to optimize the yields. The optimal labeling conditions were found to be 1 (0.1 mg, 0.17 µmol), room temperature, and 10 min for both ¹⁸ F‐NFP and ¹⁸ F‐SFB; 1 (4 mg, 6.8 µmol), 100 °C, and 10 min for ¹⁸ F‐FET. The total synthesis time, the overall yields, and the average specific activity were 105, 75, and 65 min; 68 ± 9%, 71 ± 11%, and 76 ±13%; 625 Ci/mmol, 853 Ci/mmol, and 3.5 Ci/mmol for ¹⁸ F‐FP‐ 1 ,¹⁸F‐FB‐ 1 , and ¹⁸ F‐FE‐ 1 , respectively (n = 5, decay‐corrected based on ¹⁸F). Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and in vivo evaluation of [O‐methyl‐11C] 2‐(4‐methoxyphenyl)‐N‐(4‐methylbenzyl)‐N‐(1‐methyl‐ piperidin‐4‐yl)acetamide as an imaging probe for 5‐HT2A receptors

2‐(4‐Methoxyphenyl)‐N‐(4‐methylbenzyl)‐N‐(1‐methylpiperidin‐4‐yl)acetamide (AC90179, 4 ), a highly potent and selective competitive 5‐HT_2A antagonist, was labeled by [¹¹C]‐methylation of the corresponding desmethyl analogue 5 with [¹¹C]methyl triflate. The precursor molecule 5 for radiolabeling was synthesized from p‐tolylmethylamine in three steps with 46% overall yield. [¹¹C]AC90179 was synthesized in 30 min (30 ± 5% yield, EOS) with a specific activity of 4500 ± 500 Ci/mmol and >99% chemical and radiochemical purities. Positron emission tomography studies in anesthetized baboon revealed that [¹¹C] 4 Penetrates the blood–brain barrier (BBB) with a rapid influx and efflux of the tracer in all brain regions. Due to lack of tracer retention or specific binding, [¹¹C] 4 cannot be used as PET ligand for imaging 5‐HT_2A receptors. Copyright © 2006 John Wiley & Sons, Ltd.