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Diels–Alder Adducts of Morphinan-6,8-Dienes and Their Transformations. Molecules 2022; 27:molecules27092863. [PMID: 35566212 PMCID: PMC9102320 DOI: 10.3390/molecules27092863] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 02/04/2023] Open
Abstract
6,14-ethenomorphinans are semisynthetic opiate derivatives containing an ethylene bridge between positions 6 and 14 in ring-C of the morphine skeleton that imparts a rigid molecular structure. These compounds represent an important family of opioid receptor ligands in which the 6,14-etheno bridged structural motif originates from a [4 + 2] cycloaddition of morphinan-6,8-dienes with dienophiles. Certain 6,14-ethenomorphinans having extremely high affinity for opioid receptors are often non-selective for opioid receptor subtypes, but this view is now undergoing some revision. The agonist 20R-etorphine and 20R-dihydroetorphine are several thousand times more potent analgesics than morphine, whereas diprenorphine is a high-affinity non-selective antagonist. The partial agonist buprenorphine is used as an analgesic in the management of post-operative pain or in substitution therapy for opiate addiction, sometimes in combination with the non-selective antagonist naloxone. In the context of the current opioid crisis, we communicated a summary of several decades of work toward generating opioid analgesics with lesser side effects or abuse potential. Our summary placed a focus on Diels–Alder reactions of morphinan-6,8-dienes and subsequent transformations of the cycloadducts. We also summarized the pharmacological aspects of radiolabeled 6,14-ethenomorphinans used in molecular imaging of opioid receptors.
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Meuzelaar GJ, Woudenberg RH, Sinnema A, Maat L. Synthesis of neopine and its 5β- and 7-substituted derivatives (chemistry of opium alkaloids, part XL≠). ACTA ACUST UNITED AC 2010. [DOI: 10.1002/recl.19931121103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Chen W, Strahan GD, Parrish DA, Deschamps JR, Coop A. Studies into the Diels–Alder reactions of 5-trimethylsilylthebaine. Tetrahedron Lett 2005. [DOI: 10.1016/j.tetlet.2004.11.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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