Probes for narcotic receptor mediated phenomena. 40. N-substituted cis-4a-ethyl-1,2,3,4,4a,9a-hexahydrobenzofuro[2,3-c]pyridin-8-ols

Morphine alkaloids: History, biology, and synthesis

This chapter provides a short overview of the history of morphine since it's isolation by Sertürner in 1805. The biosynthesis of the title alkaloid as well as all total and formal syntheses of morphine and codeine published after 1996 are discussed in detail. The last section of this chapter provides a detailed overview of medicinally relevant derivatives of the title alkaloid.

Probes for narcotic receptor mediated phenomena 49. N-substituted rac-cis-4a-arylalkyl-1,2,3,4,4a,9a-hexahydrobenzofuro[2,3-c]pyridin-6-ols

Racemic N-substituted -1,2,3,4,4a,9a-hexahydrobenzofuro[2,3-c]pyridin-6-ols containing cis-4a-aralkyl groups were explored as probes for opioid receptors. Specifically cis-4a-phenylpropyl, -phenylbutyl, and-phenylpentyl groups coupled with widely varied substituents on the nitrogen atom were synthesized and their pharmacological profiles at opioid receptors examined. The study yielded compounds with good affinity and moderate to potent antagonist activity at the μ- and δ-opioid receptors, and agonist activity at the κ-opioid receptor. An N-allyl substituent in the C4a phenylpropyl series induced 6-fold higher affinity at δ-than μ-receptors, while an N-CPM substituent in the C4a (CH2)3Ph series led to a compound with high δ-affinity and potent δ-antagonist activity.

Probes for narcotic receptor mediated phenomena. 47. Novel C4a- and N-substituted-1,2,3,4,4a,9a-hexahydrobenzofuro[2,3-c]pyridin-6-ols

A series of N-methyl rac-cis-4a-aralkyl- and alkyl-substituted-1,2,3,4,4a,9a-hexahydrobenzofuro[2,3-c]pyridin-6-ols have been prepared (2a-l) using a simple previously designed synthetic route, in order to find a ligand that would interact with both μ- and δ-opioid receptors. A C4a-phenethyl derivative 2a, was found to have modest receptor affinity both at μ- (K(i)=60 nM) and δ-opioid receptors (K(i)=64 nM). The N-methyl substituent of 2a and that of other ligands in the series was then modified to obtain compounds with different N-substituents that might provide higher affinity at both receptors. A number of compounds differently substituted at C4a and N were synthesized and evaluated. Binding studies and functional assays revealed a moderately selective δ-antagonist (2l), selective μ-δ antagonists (3d, 3g), and a μ-κ antagonist (3f).

Probes for narcotic receptor mediated phenomena. 41. Unusual inverse μ-agonists and potent μ-opioid antagonists by modification of the N-substituent in enantiomeric 5-(3-hydroxyphenyl)morphans

Conformational restraint in the N-substituent of enantiomeric 5-(3-hydroxyphenyl)morphans was conferred by the addition of a cyclopropane ring or a double bond. All of the possible enantiomers and isomers of the N-substituted compounds were synthesized. Opioid receptor binding assays indicated that some of them had about 20-fold higher μ-affinity than the compound with an N-phenylpropyl substituent (K(i) = 2-450 nM for the examined compounds with various N-substituents). Most of the compounds acted unusually as inverse agonists in the [(35)S]GTP-γ-S functional binding assay using nondependent cells that stably express the cloned human μ-opioid receptor. Two of the N-substituted compounds with a cyclopropane ring were very potent μ-opioid antagonists ((+)-29, K(e) = 0.17 and (-)-30, K(e) =0.3) in the [(35)S]GTP-γ-S functional binding assay. By comparison of the geometry-optimized structures of the newly synthesized compounds, an attempt was made to rationalize their μ-opioid receptor affinity in terms of the spatial position of N-substituents.