» Articles » PMID: 35566212

Diels-Alder Adducts of Morphinan-6,8-Dienes and Their Transformations

Overview
Journal Molecules
Publisher MDPI
Specialty Biology
Date 2022 May 14
PMID 35566212
Authors
Affiliations
Soon will be listed here.
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 20-etorphine and 20-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.

References
1.
Henriksen G, Willoch F . Imaging of opioid receptors in the central nervous system. Brain. 2007; 131(Pt 5):1171-96. PMC: 2367693. DOI: 10.1093/brain/awm255. View

2.
Herz A, Hollt V . [Receptor occupation and pharmacological activity as demonstrated on opiates (author's transl)]. Arzneimittelforschung. 1977; 27(96):1865-7. View

3.
Werner L, Machara A, Adams D, Cox D, Hudlicky T . Synthesis of buprenorphine from oripavine via N-demethylation of oripavine quaternary salts. J Org Chem. 2011; 76(11):4628-34. DOI: 10.1021/jo200567n. View

4.
Li F, Yang B, Miller M, Zajicek J, Noll B, Mollmann U . Iminonitroso Diels-Alder reactions for efficient derivatization and functionalization of complex diene-containing natural products. Org Lett. 2007; 9(15):2923-6. DOI: 10.1021/ol071322b. View

5.
Bentley K, Hardy D, Crocker H, Haddlesey D, Mayor P . Novel analgesics and molecular rearrangements in the morphine-thebaine group. VI. Base-catalyzed rearrangements in the 6,14-endo-ethenotetrahydrothebaine series. J Am Chem Soc. 1967; 89(13):3312-21. DOI: 10.1021/ja00989a035. View