Reaction of morphinan-6,8-dienes with azadienophiles

• Published in: Tetrahedron Vol. 52; no. 7; pp. 2449 - 2464
• Main Authors: Marton, János, Szabó, Zoltán, Csorvássy, István, Simon, Csaba, Hosztafi, Sándor, Makleit, Sándor
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 12.02.1996; Elsevier
• Subjects: Chemistry; Chemistry, Organic; Physical Sciences; Science & Technology; CHEMISTRY; THEBAINE; OPIUM-ALKALOIDS; DERIVATIVES; DIELS-ALDER REACTION
• ISSN: 0040-4020; 1464-5416; 1464-5416
• DOI: 10.1016/0040-4020(95)01066-1

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-demethoxythebaine ( 3b) with 4-phenyl-4 H-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. Reaction of various morphinandienes with PTAD afforded new Diels-Alder (DA) adducts. The retro Diels-Alder (rDA) reaction of the adducts readily proceeded in polar - aprotic solvents in the presence of bases with low nucleophilic character.