| 1. |
|
|
| 2. |
- Micskei, K., et al.
(författare)
-
Reactions of nepenthone with chromium(II) reagents in neutral aqueous medium
- 1999
-
Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1434-193X .- 1099-0690. ; :1, s. 149-153
-
Tidskriftsartikel (refereegranskat)abstract
- A synthetic method for the selective transformations of a selected morphine alkaloid in neutral aqueous medium is introduced. Full diastereoselectivity was achieved by the transformation of nepenthone (1) with [Cr(ida)(H2O)3] into 2a (20R) showing a complementary method as compared to the reactions with classical reagents to result in 2b (20S). A new unexpected morphine derivative 3 was prepared by a ligand-induced modification of the reaction which involves an unprecedented rearrangement.
|
|
| 3. |
- Marton, J., et al.
(författare)
-
Isomerization reactions of 7-substituted 6,14-bridged thebaine derivatives (Bentley compounds)
- 1998
-
Ingår i: Acta Chemica Scandinavica. - : Danish Chemical Society. - 0904-213X .- 1902-3103. ; 52:10, s. 1234-1238
-
Tidskriftsartikel (refereegranskat)abstract
- Equilibration of the 7α→7β isomers of 7-subslituted 6,14-ethenomorphinanes has been accomplished, for the first time, in dipolar aprotic solvents by the application of bases with weak nucleophilic character. Transformation of the 7β-nitrile with phenylmagnesium bromide led to a new type of 6,6′-dimeric compound.
|
|
| 4. |
- Marton, J., et al.
(författare)
-
New nepenthone and thevinone derivatives
- 1997
-
Ingår i: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896 .- 1464-3391. ; 5:2, s. 369-382
-
Tidskriftsartikel (refereegranskat)abstract
- The diastereoselective reaction of thevinone (2a) and nepenthone (2c) and their dihydro derivatives (2b and d) with Grignard reagents afforded new N-substituted (20S)- and (20R)-phenyI-6,14-ethenomorphinan derivatives (6a-y). The Grignard reaction of the N-substituted-N-demethyl derivatives 4a-f and 4m-r with methylmagnesium iodide resulted in the (20R)-phenyl tertiary alcohols 5a-f and 5m-r, respectively, but the conversion of 4g-l and that of the N-substituted-dihydrothevinone derivatives with phenylmagnesium bromide afforded the (20S)-phenyl derivatives 5g-l and 5s-y, respectively. The N-cyclopropylmethyl-, N-β-phenylethyl-, and N-propyl derivatives were prepared by the 3-O-demethylation of compounds 5. For the synthesis of the N-allyl-, N-dimethylallyl-, and N-propargyl compounds 2a-d were reacted with the corresponding Grignard reagent, and treatment of the products with cyanogen bromide gave the cyanamides 8a-d. These latter compounds were transformed into 10a,b,d, whose alkylation led to the target derivatives 6d-f, j-l, p-r, and w-y. The biochemical investigation of these substances showed that the affinities to the δ-opioid receptors were high, but the selectivity was low. Tn two cases (6c and 11d) a μ-opioid receptor specificity was observed.
|
|
| 5. |
- Marton, J., et al.
(författare)
-
Reaction of morphinan-6,8-dienes with azadienophiles
- 1996
-
Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 52:7, s. 2449-2464
-
Tidskriftsartikel (refereegranskat)abstract
- Reaction of various morphinan dienes, i.e. thebaine (1a), N-demethyl-N-formylthebaine (1b), 6-demethoxythebaine (1c), β-dihydrothebaine (2a), 4-acetoxy-β-dihydrothebaine (2b), 7-chloro-6-demethoxythebaine (3a) and 7-bromo-6-demethyoxythebaine (3b) with 4-phenyl-4H-1,2,4-triazoline-3,5-dione (PTAD) gave rise to new Diels-Alder (DA) adducts. DA-reaction of 1a, 1b and 1c with PTAD led to the products of the β-face attack of the dienophile at the diene unit. The W coupling (4J(5β,18)) in the 1H-NMR spectra was indicative of these structures. α-Face addition took place in the case of morphinan dienes with opened ring E, and a by-product was formed due to the S(E) reaction of PTAD with the adducts. The structure of these derivatives was confirmed by means of NMR spectroscopic methods. The retro Diels-Alder (rDA) reaction of the adducts 4a and 4b readily took place in polar-aprotic solvents in the presence of bases with low nucleophilic character.
|
|
| 6. |
- Marton, J., et al.
(författare)
-
Studies on the synthesis of β-thevinone derivatives
- 1998
-
Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 54:31, s. 9143-9152
-
Tidskriftsartikel (refereegranskat)abstract
- The reactions of β-thevinone and β-dihydrothevinone with tert- butylmagnesium chloride and n-propylmagnesium bromide were investigated. Further chemical transformations (N-demethylation, N-alkylation, O- demethylation) of the tertiary alcohols afforded the known β-buprenorphine and the hitherto unknown β-etorphine and β-dihydroetorphine. The by- products of these reactions were also isolated, their structures identified, and the mode of their formation was explained.
|
|
| 7. |
- Marton, J., et al.
(författare)
-
Synthesis of new nepenthone derivatives
- 1996
-
Ingår i: Liebigs Annales. - : Wiley. - 0947-3440 .- 1099-0690. ; :10, s. 1653-1656
-
Tidskriftsartikel (refereegranskat)abstract
- Hydrogenation of nepenthone (3a) leads to a mixture of dihydronepenthone (3c) and the secondary alcohol (20S)-4b. The enantiomeric secondary alcohol (20R)-4b is prepared from the 7α-formyl-6,14-ethenomorphinan derivative 3b by reaction with phenylmagnesium bromide to afford a mixture of the diastereoisomeric alcohols 4a. Hydrogenation of 4a leads to (20S)-4b and (20R)-4b, which are separated by fractional crystallization. The conformations of (20S)-4b and (20R)-4b are determined by NOE difference experiments.
|
|
| 8. |
- Szabó, Zoltan, Associate professor, et al.
(författare)
-
Conformational studies on B/C‐cis‐ and B/C‐trans‐morphinan derivatives
- 1995
-
Ingår i: Magnetic Resonance in Chemistry. - : Wiley. - 0749-1581 .- 1097-458X. ; 33:11, s. 913-916
-
Tidskriftsartikel (refereegranskat)abstract
- An unambiguous structural differentiation of B/C‐cis‐ and B/C‐trans‐morphinan derivatives (thebainone‐A and β‐thebainone‐A and their 7,8‐dihydro derivatives) is provided. The structures were confirmed by NOE difference spectroscopy and selective 2D J‐INEPT experiments. In addition, full a priori 1H and 13C NMR assignments of the isomeric pairs studied are presented.
|
|
