Search

Alzheimer’s disease (AD) is a neurodegenerative disease which affects over 50 milion people worldwide.1) AD mainly affects people ages 65 and above. Symptoms are memory loss, decline in learning capacity, and language problems. One of currently available treatments for Alzheimer's disease consists of Cholinesterase (ChEIs) inhibitors, which raise acetylcholine levels in the brain. The drugs currently approved by the FDA for this purpose are donepezil, rivastigmine and galantamine. As a part of our research we designed and synthesized seven novel compounds (6a-g) as potential acetylcholinesterase inhibitors (AChEIs). The compounds contain N-benzyl piperidine moiety, which is common in many inhibitors including donepezil,2) and N-aryl piperazine moieties.

The inhibitory activities of selected cyclic urea and carbamate derivatives (1–13) toward a-glucosidase(a-Gls) in in vitro assay were examined in this study. All examined compounds showed higher inhibitory activity (IC50) against a-Gls compared to standard antidiabetic drug acarbose. The most potent was benzyl (3,4,5-trimethoxyphenyl)carbamate (12) with IC50=49.85± 0.10μM.In vitrocytotoxicity of the investigatedcompounds was tested on three human cancer cell lines HeLa, A549 and MDA-MB-453 using MTT assay.The best antitumour activity was achieved with compound2(trans-5-phenethyl-1-phenylhexahydro-1H-imi-dazo[4,5-c]pyridin-2(3H)-one) against MDA-MB-453 human breast cancer cell line (IC50=83.41± 1.60μM).Cyclic ureas and carbamates showed promising anti-a-glucosidase activity and should be further tested as potential antidiabetic drugs. The PLS model of preliminary QSAR study indicated that, in planing the future synthesis of more potent compounds, the newly designed should have the substituents capable of polar interactions with receptor sites in various positions, while avoiding the increase of their lipophilicity.

A scalable, cost-efficient and simple synthetic pathway towards potential bivalent opioid/dopamine receptor ligands was developed and optimized. Three novel compounds that contain both opioid and dopamine pharmacophores linked by the four methylene group chain were synthesized in 33, 35 and 39 % overall yield after a four-step synthetic route starting from three commercially available N-aryl piperazines. The anilino piperidine precursor was easily prepared in three steps, as previously published, starting from 4- piperidone. The synthesis presented in this paper could be of interest for heterocyclic and general organic chemistry. The newly designed compounds possessing two pharmacophores, opioid and D2/D3, are potentially useful pharmacological probes. Of particular interest would be the simultaneous binding to both opioid and D2/D3 receptors, and the resulting pharmacological responses may be useful for the further understanding of tolerance and dependence phenomena in opioid clinical use and/or abuse. Три нова једињења, која садрже опиоидну и допаминску фармакофору, спојене преко четири метиленске групе, синтетисанa су у четири фазе у укупном приносу од приближно 35 %, полазећи од три комерцијално доступна N-арилпиперазина. Анилино- пиперидински прекурсор је добијен у три једноставне реакционе фазе, полазећи од 4-пиперидона, према познатој литературној методи. Синтеза приказана у овом раду може бити од значаја за хетероцикличну и органску хемију у целини. Новосинтетисана једињења која поседују две фармакофоре, опиоидну и Д2/Д3, су потенцијално корисни супстрати за фармаколошка испитивања. Од посебног интереса може бити истовремено везивање за опиоидне и Д2/Д3 рецепторе, а резултујући фармаколошки одговор био би користан у даљем разумевању толеранције и зависности, као феномена везаних за кли- ничку употребу и/или злоупотребу опијата.

Supplementary material for: [https://doi.org/10.1080/17518253.2016.1145744] Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/115]

Glutarimides, 2,6-dioxopiperidines, are compounds that rarely occur in natural sources, but so far isolated ones exert widespread pharmacological activities, which makes them valuable as potential pharmacotherapeutics. Glutarimides act as androgen receptor antagonists, anti-inflammatory, anxiolytics, antibacterials, and tumor suppressing agents. Some synthetic glutarimide derivatives are already in use as immunosuppressive and sedative (e.g., thalidomide) or anxiolytics (buspirone) drugs. The wide applicability of this class of compounds, justify the interest of scientists to explore new pathways for its syntheses. General methods for synthesis of six-membered imide ring are presented in this paper. These methods include: a) reaction of dicarboxylic acids with ammonia or primary amine, b) reactions of cyclization: amido-acids, diamides, dinitriles, nitrilo-acids, amidonitriles, amido-esters, amidoacyl-chlorides or diacyl-chlorides, c) addition of carbon- monoxide on α, β-unsaturated amides, d) oxidation reactions, e) Michael addition of active methylen compounds on methacrylamide or conjugated amides. Some of the described methods are used for closing glutarimide ring in syntheses of pharmacological active compounds sesbanimide and aldose reductase inhibitors (ARI). Analyses of the geometry, as well as, the spectroscopic analyses (NMR and FT-IR) of some glutarimides are presented due to their broad spectrum of pharmacological activity. To elucidate structures of glutarimides, geometrical parameters of newly synthesized tert-pentyl-1-benzyl-4-methyl-glutarimide- 3-carboxylate (PBMG) are analyzed and compared with the experimental data from X-ray analysis for glutarimide. Moreover, molecular electrostatic potential (MEP) surface which is plotted over the optimized geometry to elucidate the reactivity of PBMG molecule is analyzed. The electronic properties of glutarimide derivatives are explained on the example of thalidomide. The Frontier Molecular Orbital (FMO) and their energies are presented, as well as the energy gap between them. U ovom radu dat je prikaz metoda za sintezu šestočlanih cikličnih imida. Glutarimidi, 2,6-dioksopiperidini, su značajna biološka jedinjenja i deluju kao antagonisti adrenogenih receptora, antiinflamatorni agensi, anksiolitici, antivirotici, antibiotici i agensi koji sprečavaju rast pojedinih vrsta tumora. Prikazana je i njihova spektralna analiza (FT-IR i NMR), zbog potvrde stukture, kao i analiza graničnih molekulskih orbitala koja daje prikaz elektronskih svojstava ovih molekula, što je važno zbog njihove biološke aktivnosti. Da bi se predstavila hemijska reaktivnost glutarimida predstavljen je molekulski elektronski potencijal (MEP) iz prethodno optimizovane geometrije reprezentativnog primera terc-pentil-1- -benzil-4-metil-glutarimid-3-karboksilata (skraćenica PBMG). Elektronska svojstva su objašnjena na primeru talidomida.

Glutarimides, 2,6-dioxopiperidines, are compounds that rarely occur in natural sources, but so far isolated ones exert widespread pharmacological activities, which makes them valuable as potential pharmacotherapeutics. Glutarimides act as androgen receptor antagonists, anti-inflammatory, anxiolytics, antibacterials, and tumor suppressing agents. Some synthetic glutarimide derivatives are already in use as immunosuppressive and sedative (e.g., thalidomide) or anxiolytics (buspirone) drugs. The wide applicability of this class of compounds, justify the interest of scientists to explore new pathways for its syntheses. General methods for synthesis of six-membered imide ring are presented in this paper. These methods include: a) reaction of dicarboxylic acids with ammonia or primary amine, b) reactions of cyclization: amido-acids, diamides, dinitriles, nitrilo-acids, amidonitriles, amido-esters, amidoacyl-chlorides or diacyl-chlorides, c) addition of carbon-monoxide on alpha,beta-unsaturated amides, d) oxidation reactions, e) Michael addition of active methylen compounds on methacrylamide or conjugated amides. Some of the described methods are used for closing glutarimide ring in syntheses of pharmacological active compounds sesbanimide and aldose reductase inhibitors (ARI). Analyses of the geometry, as well as, the spectroscopic analyses (NMR and FT-IR) of some glutarimides are presented due to their broad spectrum of pharmacological activity. To elucidate structures of glutarimides, geometrical parameters of newly synthesized tert-pentyl-1-benzyl-4-methyl-glutarimide-3-carboxylate (PBMG) are analyzed and compared with the experimental data from X-ray analysis for glutarimide. Moreover, molecular electrostatic potential (MEP) surface which is plotted over the optimized geometry to elucidate the reactivity of PBMG molecule is analyzed. The electronic properties of glutarimide derivatives are explained on the example of thalidomide. The Frontier Molecular Orbital (FMO) and their energies are presented, as well as the energy gap between them. U ovom radu dat je prikaz metoda za sintezu šestočlanih cikličnih imida. Glutarimidi, 2,6-dioksopiperidini, su značajna biološka jedinjenja i deluju kao antagonisti adrenogenih receptora, antiinflamatorni agensi, anksiolitici, antivirotici, antibiotici i agensi koji sprečavaju rast pojedinih vrsta tumora. Prikazana je i njihova spektralna analiza (FT-IR i NMR), zbog potvrde stukture, kao i analiza graničnih molekulskih orbitala koja daje prikaz elektronskih svojstava ovih molekula, što je važno zbog njihove biološke aktivnosti. Da bi se predstavila hemijska reaktivnost glutarimida predstavljen je molekulski elektronski potencijal (MEP) iz prethodno optimizovane geometrije reprezentativnog primera terc-pentil-1- -benzil-4-metil-glutarimid-3-karboksilata (skraćenica PBMG). Elektronska svojstva su objašnjena na primeru talidomida.

Introduction. Fentanyl belongs to 4-anilidopiperidine class of synthetic opioid analgesics. It is characterized by high potency, rapid onset and short duration of action. A large number of fentanyl analogues have been synthesized so far, both to establish the structure-activity-relationship (SAR) and to find novel, clinically useful analgesic drugs. Objective. In this study, newly synthesized 3-alkyl fentanyl analogues were examined for analgesic activity and compared with fentanyl. Methods. Analgesic activity was assessed by tail-immersion test in rats. Results. The relative potency was: (±)cis-3-methyl fentanyl (8) gt (±)trans-3-methyl fentanyl (2) $ (±)cis-3-ethyl fentanyl (1.5) gt fentanyl (1) $ (±)trans-3-ethyl fentanyl (0.9) gt (±)cis-3-butyl fentanyl (0.064) $ (±)trans-3-butyl fentanyl (0.035) gt (±)cis-3-benzyl fentanyl (0.008) $ (±)trans-3-benzyl fentanyl (0.0055). (±)Cis-3-iso-propyl fentanyl, and (±)cis-3-phenethyl fentanyl are inactive in doses up to 5 mg/kg. The duration of action (ED99) was: (±)cis-3-methyl fentanyl (90 min) gt (±)trans-3-methyl fentanyl (40 min) # (±)cis-3-ethyl fentanyl (60 min) $ (±)trans-3-ethyl fentanyl (40 min) # fentanyl (50 min) = (±)cis-3-butyl fentanyl (50 min) = (±)trans-3-butyl fentanyl (50 min) = (±)cis-3-benzyl fentanyl (50 min) = (±)trans-3-benzyl fentanyl (50 min). Symbols gt and lt denotes p lt 0.05. Conclusion. It is concluded that the analgesic potency of 3-alkyl fentanyl analogues is influenced by the steric factor (voluminosity of the group at the position 3 of the piperidine ring and the cis/trans isomerism). Otherwise, with the exception of 3-methyl fentanyl, the duration of action of 3-alkyl fentanyl analogues is not significantly affected by the stereochemistry. Uvod. Fentanil pripada grupi sintetskih opioidnih analgetika, 4-anilidopiperidina. Karakteriše ga visoka potentnost, brz početak i kratko trajanje dejstva. Do sada je sintetisan veliki broj analoga fentanila, kako u cilju određivanja odnosa strukture i farmakološke aktivnosti, tako i u cilju pronalaženja novog klinički korisnog analgetika. Cilj rada. U studiji su ispitivana analgetska dejstva novosintetisanih 3-alkil analoga fentanila i poređena sa fentanilom. Metod rada. Merenje analgetskog dejstva ispitivanih jedinjenja vršeno je uz pomoć testa potapanja repa pacova u toplu vodu. Rezultati. Relativna jačina jedinjenja iznosila je: (±)cis-3-metil fentanil (8) gt (±)trans-3-metil fentanil (2) $ (±)cis-3-etil fentanil (1,5) gt fentanil (1) $ (±)trans-3-etil fentanil (0,9) gt (±)cis-3-butil fentanil (0,064) $ (±)trans-3-butil fentanil (0,035) gt (±)cis-3-benzil fentanil (0,008) $ (±)trans-3-benzil fentanil (0,0055). (±)Cis-3-izopropil fentanil i (±)cis-3-fenetil fentanil nisu ispoljili dejstvo u dozama do 5 mg/kg. Dužina dejstva (ED99) iznosila je: (±)cis-3-metil fentanil (90 min) gt (±)trans-3-metil fentanil (40 min) # (±)cis-3-etil fentanil (60 min) $ (±)trans-3-etil fentanil (40 min) # fentanil (50 min) = (±)cis-3-butil fentanil (50 min) = (±)trans-3-butil fentanil (50 min) = (±)cis-3-benzil fentanil (50 min) = (±)trans-3-benzil fentanil (50 min). Oznake gt i lt označavaju P lt 0.05. Zaključak Zaključeno je da na analgetsku jačinu 3-alkil analoga fentanila utiče sterni faktor (voluminoznost grupe na položaju 3 piperidinskog prstena i cis/trans izomerizam). Inače, uz izuzetak 3-metil fentanila, stereohemija ne utiče značajno na dužinu dejstva 3-alkil analoga fentanila.

An automated docking procedure was applied to study the binding of a series of mu- and delta-selective ligands to ligand-specific mu- and delta-opioid receptor models. Short-time molecular dynamic simulations were used to obtain ligand-specific mu- and delta-opioid receptors from arbitrarily chosen models of the active form of these receptors. The quality of receptor model depended on the molecular volume of the ligand in the receptor-ligand complex used in the molecular dynamic simulations. Within a series of ligands of similar size (volume), the results of ligand docking to the obtained ligand-specific receptor conformation were in agreement with point mutation studies. The correlation of the calculated and the experimentally determined binding energies was improved in relation to the initial receptor conformation. Računska metoda automatizovanog dokiranja primenjena je na vezivanje serije liganada, specifičnih za µ- i δ-receptore, za modele ovih receptora. Kratkotrajna molekulsko dinamička simulacija je korišćena za dobijanje konformacija ovih receptora koje su specifične za pojedine ligande, polazeći od slučajno izabranog modela aktiviranog receptora. Kvalitet ovako dobijenog modela receptora zavisi od molekulske zapremine liganda u ligand-receptor kompleksu korišćenog u molekulsko-dinamičkoj simulaciji. Za seriju liganda slične zapremine rezultati dokiranja su u skladu sa eksperimentalnim rezltatima mutacija aminokiselina u receptoru. Korelacija izračunatih i merenih energija vezivanja je poboljšana u odnosu na rezultate dobijene sa polaznom konformacijom receptora.

Levels of nitric oxide (NO) in the rats frontal cortex were continuously monitored before and after intraperitoneal administration of an antiepileptic drug-pentobarbital (20 and 40 mg/kg) or convulsant drug - pentylenetetrazol (50 mg/kg). Pentobarbital decreased the levels of NO in a dose dependent manner However, NO levels had a tendency to increase following the administration of pentylenetetrazol. It is suggested that central NO participates in the modulation of neuronal excitability, supporting the idea that NO is an important excitatory factor involved in the regulation of seizure susceptibility. Also, our results on anaesthetized rats suggests that endogenous NO may be involved in the mechanism of action of antiepileptic and analeptic drugs and this further suggest that NO levels in the human brain may decrease during antiepileptic therapy and increase during epileptic attacks or administration of excitatory drugs. The aim of the present study was to determine the possible role of NO levels in the brain during neuronal excitability and seizures. Nivo azot oksida (NO) u frontalnom korteksu pacova meren je kontinuirano kako pre, tako i nakon intraperitonealne primene antiepileptika pentobarbitala (u dozi od 20 i 40 mg/kg) ili konvulzivnog agensa pentilenetetrazola (u dozi od 50 mg/kg). Rezultati ovih eksperimenta su ukazali da pentobarbital smanjuje nivo NO u frontalnom korteksu pacova, dok koncentracija NO ima tendeciju rasta nakon primene pentilenetetrazola. Osim toga, dokazano je da endogeni NO ima važnu ekscitatornu ulogu u centralnim mehanizmima nastanka epilepsije. Takođe, naši rezultati su ukazali da kod anestetisanih životinja endogeni nivo NO ima uticaja na dejstvo kako antikonvulzivnih, tako i prokonvulzivnih lekova. Nivo NO u mozgu pacova je bio snižen tokom terapije antiepilepticima, a povišen tokom epileptičkih napada ili primene lekova iz grupe centralnih stimulansa.

A general five step method for the synthesis of 3-alkylfentanyl analogues (i.e. cis and trans 3-alkyl-4-anilidopiperidines 6.1-6.6) has been developed, The starting N-phenethyl-4-piperidone 1 was first converted into the cyclohexylimine derivative 2. alpha-deprotonated with butyllithium and die resulting imine anion efficiently monoalkylated with primary, and secondary alkyl halides. After mild acid hydrolysis. the obtained 3-alkyl-4-piperidones 3.1-3.6 were isolated in good yields (79-85%), then condensed with aniline to form imines 4.1-4.6. Subsequent reduction of the imines (LiAlH4/THF) yielded cis/trans mixtures of 3-alkyl-4-anilinopiperidines 5.1-5.6. Quantitative separation of the diastereoisomers by column chromatography of Al2O3 gave pure cis 5.1-5.6 (29-51% yield) and trans 5.1-5.6 (19-27% yield), with the cis/trans ratio in the range 7/3-6/4 . The synthesis was concluded by N-acylation of the purified 5.1-5.6, with propionyl chloride, to afford cis and trans 3-alkyl-4-anilidopiperidines 6.1-6.6 (approximate to 95% yield, as monooxalate salts). No enatioseparation was attempted at any stage. The relative cis/trans stereochemistry was provisionally assigned from the H-1-NMR spectra. Of the twelve synthesized 3-alkylfentanyls. ten compounds (two known and eight novel derivatives, all as the monooxalate salts) were preliminarily tested as analgesics in rats, comparing the potency to fentanyl. Except for the known (+/-)-cis-3-Me fentanyl 6.1cis. (8 x fentanyl), and the novel (+/-)-cis-3-Et fentanyl 6.2cis. (1.5 x fentanyl), all of the others were less active than fentanyl or inactive. Some tentative conclusions on the structure-activity relationship (SAR) in this series of derivatives have been made. Razvijen je opšti metod za sintezu 3-alkil analoga fentanila (tj. cis i trans 3-alkil-4-anilidopiperidina 6.1–6.6) u pet faza. Polazni N-fenetil-4-piperidon 1 prvo je preveden u cikloheksiliminski derivat 2, α-deprotonovan butillitijumom, a postali iminski anjon efikasno monoalkilovan primarnim i sekundarnim alkilhalogenidima. Posle blage kisele hidrolize, nastali 3-alkil-4-piperidoni 3.1–3.6 izolovani su u dobrim prinosima (79–85 %), zatim kondenzovani sa anilinom do imina 4.1–4.6. Redukcijom ovih imina (LiAlH4/THF) dobijene su cis/trans smese 3-alkil-4-anilinopiperidina 5.1–5.6. Kvantitativnim hromatografskim razdvajanjem dijastereoizomera na stubu Al2O3 izolovani su čisti cis 5.1–5.6 (prinos 29–51 %) i trans 5.1–5.6 (prinos 19–27 %), gde je cis/trans odnos bio u opsegu 7/3–6/4. Sinteza je završena N-acilovanjem prečišćenih intermedijera 5.1–5.6 pomoću propionil-hlorida, pri čemu su postali cis i trans 3-alkil-4-anilidopiperidini 6.1–6.6 (prinos _ 95 %, kao monooksalatne soli). Ni u jednoj fazi nije pokušano razdvajanje enantiomera. Relativna, cis/trans, stereohemija preliminarno je određena iz 1H-NMRspektra. Od dvanaest sintetisanih 3-alkil-fentanila, deset jedinjenja (dva poznata i osam novih, sva u obliku monookasalatnih soli) preliminarno su testirana kao analgetici na pacovima, poredeći aktivnost sa fentanilom.Osim poznatog (±)-cis-3-Me fentanila 6.1 cis, (8 x fentanil), i novog (±)-cis-3-Et fentanila 6.2 cis, (1,5 x fentanil), svi ostali bili su manje aktivni ili neaktivni. Izvedeni su određeni, preliminarni zaključci u vezi odnosa strukture i aktivnosti u ovoj seriji derivata.

An efficient, five-step synthetic approach to various acyclic 1,3-diamines has been developed and applied to the preparation of a novel class of open-chained fentanyl analogues. The acyclic derivatives 5.1-5.5 (all new compounds) were synthesized with the aim of estimating the significance of the piperidine ring for the opioid analgesic activity of anilido-piperidines. The starting beta-keto-amide 1.1, prepared by the aminolysis of methyl acetoacetate with methyl phenethylamine, (93% yield), was successively reacted with NaH and BuLi, to form the highly reactive alpha,gamma-dienolate anion 1.1a. Regio and chemoselective gamma-alkylation of the dienolate with various primary and secondary alkyl halides furnished the beta-keto-amides 1.2-1.5 (76-91%). Reductive amination of the keto-amides 1.1-1.5 with aniline and Zn powder in acetic acid, via the enamine intermediates 2.1-2.5. afforded the beta-anilino amides 3.1-3.5 (74-85%). After reductive deoxygenation of the tertiary amide group, using in situ generated diborane, the corresponding 1,3-diamines 4.1-4.5 were obtained (87-97%). The synthesis of (+/-)-2,3-seco-fentanyls 5.1-5.5 was completed by N-acylation of the diamines 4.1-4.5 with propionyl chloride, followed by precipitation of the monooxalate salts (86-95%). The parent compound, 2,3-seco-fentanyl 5.1, was found to be a 40 times less potent narcotic analgesic than fentanyl but still 5-6 times more active than morphine in rats. while i-Pr derivative 5.3 was inactive. Apart from the pharmacological significance. the general procedure described herein may afford various functionalized, 1,3-diamines as potential complexing agents and building blocks for the synthesis of aza-crown ethers. Razvijen je efikasan postupak za dobijanje različitih acikličnih 1,3-diamina u pet faza, i primenjen u sintezi nove klase analoga fentanila otvorenog niza. Derivati 5.1–5.5 (svi su nova jedinjenja) sintetisani su sa ciljem da se proceni uticaj piperidinskog prstena na opioidnoanalgetičku aktivnost anilido-piperidina. Polazni β-keto-amid 1.1, dobijen aminolizom metilacetoacetata metilfenetilaminom (prinos 93 %), bio je sukcesivno tretiran sa NaH i BuLi, pri čemu je postao veoma reaktivni α,γ-dienolatni anjon 1.1a. Regio- i hemoselektivnim γ-alkilovanjem ovog dienolata različitim primarnim i sekundarnim alkil-halogenidima, dobijeni su β-keto-amidi 1.2–1.5 (prinos 76–91 %). Reduktivnim aminovanjem keto-amida 1.1–1.5 pomoću Zn praha i sirćetne kiseline, preko enaminskih intermedijera 2.1–2.5, postali su -anilino-amidi 3.1–3.5 (prinos 74–85 %). Posle reduktivne deoksigenacije tercijene amidne funkcije, koristeći in situ generisani diboran, odgovarajući 1,3-diamini 4.1–4.5 izolovani su u prinosima 87–97 %. Sinteza (±)-2,3-seco-fentanila 5.1–5.5 završena je N-acilovanjem diamina 4.1–4.5 propionil-hloridom, a zatim taloženjem u obliku monooksalatnih soli (prinos 86–95 %). Nađeno je da je osnovno jedinjenje, 2,3-seco fentanil 5.1, 40 puta slabiji narkotički analgetik od fentanila, ali još uvek 5–6 puta aktivniji od morfina u pacova, dok je i-Pr derivat 5.3 bio neaktivan. Osim farmakološkog značaja, opštim postupkom prikazanim u ovom radu, mogu se sintetisati različiti 1,3-diamini, uključujući i one sa funkcionalnim grupama. Ova jedinjenja mogu biti potencijalno značajna kao kompleksirajući agensi i kao intermedijeri u sintezi aza-kraun-etara.

An efficient synthesis of methyl 4-[(1-oxopropyl)phenylamino]piperidine-4-carboxylate (7) has been developed, starting from 1-benzylpiperidin-4-one (1), The compound is a key intermediate in the synthesis of new generation, highly active narcotic analgesics, such as remifentanil. as well as the novel classes of fentanyl analogues, An optimized Strecker-type condensation of piperidone 1 with aniline and HCN yielded the anilino-nitrile 2 (approximate to90%) which, upon selective hydrolysis with cone. H2SO4, gave the anilino-amide 3. After vigorous basic hydrolysis of 3, followed by acidification and successive treatment with SOCl2 and MeOH, the anilino-ester 5 was obtained (40-45%, in 3 steps). N-Acylation of 5 with propionyl chloride yielded the anilido-ester 6 (70-80%). In the final step, the catalytic N-debenzylation of 6 was examined under various conditions and optimized to yield 7 in near quantitative yields. U ovom radu razvijena je efikasna sinteza metil 4-[(1-oksopropil)fenilamino]piperidin-4-karboksilata (7), prolazeći od 1-benzil piperidin-4-on-1 (1). Jedinjenje 7 je ključni intermedijer u sintezi nove generacije visoko aktivnih narkotičkih analgetika, kao što je remifentanil a takođe i novih klasa analoga fentanyla. U optimizovanoj Strecker-ovoj kondenzaciji priperidona 1 sa anilinom i HCN, dobijen je anilino-nitril 2 (≈90%) prinos čijom je selektivnom hidrolizom pomoću konc. H2SO4 postao anilino-amid 3. Intenzivnom baznom hidrolizom ovog intermedijera, zakišeljavanjem a zatim sukcesivno reakcijom sa SOCl2 i MeOH sintetisan je anilino-estar 5 (≈40–45% prinos u 3 faze). N-acelovanjem anilino-estra 5 sa propionil hloridom postao je anilido-estar 6 (≈70–80% prinos). U poslednjom fazi sinteze izvršena je optimizacija katalitičkog N-debenzilovanja anilido-estra 6 do finalnog proizvoda 7, u približno kvantitativnom prinosu.