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Popov KK, Campbell JLP, Kysilka O, Hošek J, Davies CD, Pour M, Kočovský P. Reductive Amination Revisited: Reduction of Aldimines with Trichlorosilane Catalyzed by Dimethylformamide─Functional Group Tolerance, Scope, and Limitations. J Org Chem 2021; 87:920-943. [PMID: 34841878 DOI: 10.1021/acs.joc.1c01561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Aldimines, generated in situ from aliphatic, aromatic, and heteroaromatic aldehydes and aliphatic, aromatic, and heteroaromatic primary or secondary amines, can be reduced with trichlorosilane in the presence of dimethylformamide (DMF) as an organocatalyst (≤10 mol %) in toluene or CH2Cl2 at room temperature. The reduction tolerates ketone carbonyls, esters, amides, nitriles, sulfones, sulfonamides, NO2, SF5, and CF3 groups, boronic esters, azides, phosphine oxides, C═C and C≡C bonds, and ferrocenyl nucleus, but sulfoxides and N-oxides are reduced. α,β-Unsaturated aldimines undergo 1,2-reduction only, leaving the C═C bond intact. N-Monoalkylation of primary amines is attained with a 1:1 aldehyde to amine ratio, whereas excess of the aldehyde (≥2:1) allows second alkylation, giving rise to tertiary amines. Reductive N-alkylation of α-amino acids proceeds without racemization; the resulting products, containing a C≡C bond or N3 group, are suitable for click chemistry. This reaction thus offers advantages over the traditional methods (borohydride reduction or catalytic hydrogenation) in terms of efficiency and chemoselectivity. Solubility of some of the reacting partners appears to be the only limitation. The byproducts generated by the workup with aqueous NaHCO3 (i.e., NaCl and silica) are environmentally benign. As a greener alternative, DMA can be employed as a catalyst instead of DMF.
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Affiliation(s)
- Kirill K Popov
- Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague 2, Czech Republic
| | - Joanna L P Campbell
- Syngenta, Grangemouth Manufacturing Centre, Earl's Road, Grangemouth FK3 8XG, U.K
| | - Ondřej Kysilka
- Trelleborg Bohemia, Akademika Bedrny 531/8a, Věkoše, 500 03 Hradec Králové Czech Republic
| | - Jan Hošek
- Farmak, Na vlčinci 16/3, Klášterní Hradisko, 77900 Olomouc, Czech Republic
| | | | - Milan Pour
- Department of Organic and Bioorganic Chemistry, Faculty of Pharmacy, Charles University, Heyrovského 1203, 500 05 Hradec Králové, Czech Republic
| | - Pavel Kočovský
- Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague 2, Czech Republic.,Department of Organic and Bioorganic Chemistry, Faculty of Pharmacy, Charles University, Heyrovského 1203, 500 05 Hradec Králové, Czech Republic.,Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo 2, 166 10 Prague 6, Czech Republic
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2
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Synthesis and in vivo brain distribution of carbon-11-labeled δ-opioid receptor agonists. Nucl Med Biol 2010; 37:989-96. [PMID: 21055630 DOI: 10.1016/j.nucmedbio.2010.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 05/20/2010] [Accepted: 06/01/2010] [Indexed: 11/23/2022]
Abstract
Three new radiolabeled compounds, [(11)C]SNC80 ((+)-4-[(αR)-α-{(2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl}-3-[(11)C]methoxybenzyl-N,N-diethylbenzamide), N,N-diethyl-4-[3-methoxyphenyl-1-[(11)C]methylpiperidin-4-ylidenemethyl)benzamide and N,N-diethyl-4-[(1-[(11)C]methylpiperidin-4-ylidene)phenylmethyl]benzamide, were prepared as potential in vivo radiotracers for the δ-opioid receptor. Each compound was synthesized by alkylation of the appropriate desmethyl compounds using [(11)C]methyl triflate. In vivo biodistribution studies in mice showed very low initial brain uptake of all three compounds and no regional specific binding for [(11)C]SNC80. A monkey positron emission tomography study of [(11)C]SNC80 confirmed low brain permeability and uniform regional distribution of this class of opioid agonists in a higher species. Opioid receptor ligands of this structural class are thus unlikely to succeed as in vivo radiotracers, likely due to efficient exclusion from the brain by the P-glycoprotein efflux transporter.
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Nonpeptidic Delta (δ) Opioid Agonists and Antagonists of the Diarylmethylpiperazine Class: What Have We Learned? Top Curr Chem (Cham) 2010; 299:121-40. [DOI: 10.1007/128_2010_83] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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4
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Straightforward three-component synthesis of diarylmethylpiperazines and 1,2-diarylethylpiperazines. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.02.086] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Jung B, Englberger W, Wünsch B. Molecular modeling directed synthesis of a bicyclic analogue of the δ opioid receptor agonist SNC 80. Arch Pharm (Weinheim) 2005; 338:281-90. [PMID: 15938001 DOI: 10.1002/ardp.200400994] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In order to find novel delta opioid receptor agonists, the pharmacophoric benzhydryl moiety of the lead compound SNC 80 (1) was dissected and the phenyl residues were attached to different positions of the 6,8-diazabicyclo[3.2.2]nonane core system (4). The position of the carboxamido group, the stereochemistry, the C3/C4 bond order and the kind and length of the spacer X were considered. The resulting compounds were compared with the four energetically most favourable conformations of SNC 80 by a multifit analysis. These calculations led to the structures 5-10, which fit best to SNC 80. Herein the synthesis of one of these compounds (9) is described. Starting from (S)-glutamate two alternative routes are detailed to obtain the key intermediate 14. A variation of the Dieckmann cyclization, which uses trapping of the first cyclization product with ClSiMe(3) provided the mixed acetal 20, which was carefully hydrolyzed to yield the bicyclic ketone 17. Stereoselective addition of phenylmagnesium bromide, dehydration, LiAlH(4) reduction and exchange of the N-6 residue afforded the designed compound 9. The affinities of 9 towards delta, mu, kappa and ORL1 receptors were determined in receptor binding studies with radioligands. Only moderate receptor affinity was found.
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Affiliation(s)
- Bettina Jung
- Institut für Pharmazeutische und Medizinische Chemie, Münster, Germany
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Carson JR, Coats SJ, Codd EE, Dax SL, Lee J, Martinez RP, Neilson LA, Pitis PM, Zhang SP. N,N-dialkyl-4-[(8-azabicyclo[3.2.1]-oct-3-ylidene)phenylmethyl]benzamides, potent, selective delta opioid agonists. Bioorg Med Chem Lett 2004; 14:2109-12. [PMID: 15080989 DOI: 10.1016/j.bmcl.2004.02.051] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2003] [Accepted: 02/10/2004] [Indexed: 11/30/2022]
Abstract
A series of N,N-dialkyl-4-(9-aryltropanylidenemethyl)benzamides was prepared. The lead compounds, 15a and 15c, exhibited extremely high affinity for the delta opioid receptor with excellent selectivity versus the micro opioid receptor. They were full agonists at the delta opioid receptor, as assessed by stimulation of GTPgammaS binding, and displayed antinociceptive activity.
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Affiliation(s)
- John R Carson
- Drug Discovery, Johnson and Johnson Pharmaceutical Research and Development, LLC, Welsh and McKean Roads, PO 776, Spring House, PA 19477-0776, USA.
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Coats SJ, Schulz MJ, Carson JR, Codd EE, Hlasta DJ, Pitis PM, Stone DJ, Zhang SP, Colburn RW, Dax SL. Parallel methods for the preparation and SAR exploration of N-ethyl-4-[(8-alkyl-8-aza-bicyclo[3.2.1]oct-3-ylidene)-aryl-methyl]-benzamides, powerful mu and delta opioid agonists. Bioorg Med Chem Lett 2004; 14:5493-8. [PMID: 15482911 DOI: 10.1016/j.bmcl.2004.09.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Revised: 09/01/2004] [Accepted: 09/03/2004] [Indexed: 11/18/2022]
Abstract
Two parallel synthetic methods were developed to explore the structure-activity relationships (SAR) of a series of potent opioid agonists. This series of tropanylidene benzamides proved extremely tolerant of structural variation while maintaining excellent opioid activity. Evaluation of several representative compounds from this series in the mouse hot plate test revealed potent antinociceptive effects upon oral administration.
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Affiliation(s)
- Steven J Coats
- Drug Discovery, Johnson and Johnson Pharmaceutical Research and Development, L.L.C., Welsh and McKean Roads, PO Box 776, Spring House, PA 19477-0776, USA.
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Kim IJ, Ullrich T, Janetka JW, Furness MS, Jacobson AE, Rothman RB, Dersch CM, Flippen-Anderson JL, George C, Rice KC. Diaryldimethylpiperazine ligands with μ- and δ-opioid receptor affinity: Synthesis of (+)-4-[(αR)-α-(4-allyl-(2S,5S)-dimethylpiperazin-1-yl)-(3-hydroxyphenyl)methyl]-N-ethyl-N-phenylbenzamide and (−)-4-[(αR)-α-(2S,5S)-dimethylpiperazin-1-yl)-(3-hydroxyphenyl)methyl]-N-ethyl-N-phenylbenzamide. Bioorg Med Chem 2003; 11:4761-8. [PMID: 14556791 DOI: 10.1016/s0968-0896(03)00496-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have explored the synthesis of compounds that have good affinity for both mu- and delta-opioid receptors from the (alphaR,2S,5S) class of diaryldimethylpiperazines. These non-selective compounds were related to opioids that have been found to interact selectively with mu- or delta-opioid receptors as agonists or antagonists. In our initial survey, we found two compounds, (+)-4-[(alphaR)-alpha-(4-allyl-(2S,5S)-dimethylpiperazin-1-yl)-(3-hydroxyphenyl)methyl]-N-ethyl-N-phenylbenzamide (14) and its N-H relative, (-)-4-[(alphaR)-alpha-(2S,5S)-dimethylpiperazin-1-yl)-(3-hydroxyphenyl)methyl]-N-ethyl-N-phenylbenzamide (15), that interacted with delta-receptors with good affinity, and, as we hoped, with much higher affinity at mu-receptors than SNC80. The relative configuration of the benzylic position in (+)-4-[(alphaR)-alpha-(4-allyl-(2S,5S)-dimethyl-1-piperazinyl)-(3-methoxyphenyl)methyl]-benzyl alcohol (10) was determined by X-ray crystallographic analysis of a crystal that was an unresolved twin. The absolute stereochemistry of that benzylic stereogenic center was unequivocally derived by the X-ray crystallographic analysis from the two other centers of asymmetry in the molecule that were known. Those were established from the synthesis via a dipeptide cyclo-L-Ala-L-Ala in which the absolute stereochemistry was established.
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MESH Headings
- Animals
- Benzamides/chemical synthesis
- Benzamides/chemistry
- Benzamides/metabolism
- Benzamides/pharmacology
- Brain/metabolism
- Cell Membrane/metabolism
- Crystallography, X-Ray
- Guinea Pigs
- Ligands
- Molecular Conformation
- Molecular Structure
- Piperazines/chemical synthesis
- Piperazines/chemistry
- Piperazines/metabolism
- Piperazines/pharmacology
- Radioligand Assay
- Rats
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Stereoisomerism
- Structure-Activity Relationship
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Affiliation(s)
- In Jong Kim
- Laboratory of Medicinal Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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9
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McFadyen IJ, Metzger TG, Paterlini MG, Ferguson DM. Exploring the unique pharmacology of a novel opioid receptor, ZFOR1, using molecular modeling and the 'message-address' concept. Protein Eng Des Sel 2001; 14:953-60. [PMID: 11809925 DOI: 10.1093/protein/14.12.953] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Previous studies have probed the structural basis of ligand selectivity in the mu, delta and kappa opioid receptors through the application of molecular modeling techniques in concert with the 'message-address' concept. Here, this approach was used in an attempt to rationalize the unique pharmacological profile of a recently cloned novel opioid receptor, ZFOR1 (ZebraFish Opioid Receptor 1). Specifically, a model of the transmembrane domains of ZFOR1 was constructed and used to explore the binding modes of various prototypical opioid ligands. The results show that the 'message' portion of the binding pocket of ZFOR1 is highly conserved; hence, the binding modes of non-selective opioid ligands are well preserved. In contrast, a small number of variant residues at the extracellular end of the binding pocket, particularly Lys288 (VI:26) and Trp304 (VII:03), are shown to create adverse steric interactions with all delta and kappa selective ligands examined, thereby disrupting their binding modes. These results are consistent with, and serve as an explanation for, the observed pharmacology of this receptor, lending support to both the validity of the 'message-address' concept itself and to the use of molecular modeling approaches in its application.
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Affiliation(s)
- I J McFadyen
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55414, USA
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10
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Thomas JB, Atkinson RN, Rothman RB, Burgess JP, Mascarella SW, Dersch CM, Xu H, Carroll FI. 4-[(8-Alkyl-8-azabicyclo[3.2.1]octyl-3-yl)-3-arylanilino]-N,N-diethylbenzamides: high affinity, selective ligands for the delta opioid receptor illustrate factors important to antagonist activity. Bioorg Med Chem Lett 2000; 10:1281-4. [PMID: 10866400 DOI: 10.1016/s0960-894x(00)00209-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The tropane derived compounds, 4-[(8-alkyl-8-azabicyclo[3.2.1]octyl-3-yl)-3-arylanilino]-N,N-d iethylbenzamides (5a-d), were synthesized and found to have high affinity and selectivity for the delta receptor. Compounds 5a-d are structurally similar to the full agonist (-)-RTI-5989-54 (3); yet, efficacy studies for compounds in this series (5a-d) reveal greatly diminished agonist activity as well as antagonism not found in piperidine-based compounds like 3.
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Affiliation(s)
- J B Thomas
- Chemistry and Life Sciences, Research Triangle Institute, Research Triangle Park, NC 27709, USA
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11
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Boyd RE, Carson JR, Codd EE, Gauthier AD, Neilson LA, Zhang SP. Synthesis and binding affinities of 4-diarylaminotropanes, a new class of delta opioid agonists. Bioorg Med Chem Lett 2000; 10:1109-11. [PMID: 10843229 DOI: 10.1016/s0960-894x(00)00182-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
A series of 4-diarylaminotropanes has been prepared. Both endo and exo diastereomeric forms bound to the delta opioid receptor but the endo isomers were more potent and selective versus the mu opioid receptor than the exo isomers. The most potent delta opioid agonist (14) exhibited a delta opioid Ki of 0.2 nM and was 860-fold selective over mu.
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MESH Headings
- Animals
- Benzamides/metabolism
- Binding Sites
- Diphenylamine/analogs & derivatives
- Diphenylamine/chemistry
- Diphenylamine/metabolism
- Diphenylamine/pharmacology
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/metabolism
- Enkephalin, D-Penicillamine (2,5)-/metabolism
- Morphine/metabolism
- Piperazines/metabolism
- Rats
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/metabolism
- Stereoisomerism
- Structure-Activity Relationship
- Tropanes/chemistry
- Tropanes/metabolism
- Tropanes/pharmacology
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Affiliation(s)
- R E Boyd
- Drug Discovery, R. W. Johnson Pharmaceutical Research Institute, Spring House, Philadelphia, PA 19477, USA
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