Oxydative Kondensationen quartärer phenolischer Basen

Abstract

Einfache phenolische Basen können in Anlehnung an die Biosynthese mit guter Ausbeute oxydativ zu Alkaloiden der Isochinolin‐Gruppe kondensiert werden, wenn deren Stickstoff quartär ist. Auf diese Weise wurden mehr als 60 Alkaloide verschiedener Strukturtypen besser zugänglich. Von den zahlreichen möglichen Kondensationen der zwischendurch gebildeten mesomeren Radikale erfolgten dabei nur diejenigen, die zu natürlichen Alkaloiden führen. Die Befunde lassen vermuten, daß die oxydative Kondensation quartärer Basen auch bei der Alkaloid‐Biosynthese in der Pflanzenzelle eine Rolle spielt.

Synthesis of novel (benzimidazolyl)isoquinolinols and evaluation as adenosine A1 receptor tools

“…Since there are only two reports 25,43 for non-metal-mediated aromatisation of unprotected tetrahydroisoquinolinol to isoquinolinol, for which experimental details are unclear and no yields are provided, the method described herein using DDQ and atmospheric oxygen in mild conditions will prove useful for the preparation of biologically important isoquinolines and isoquinolinols.…”

Aromatic Azopolymers Produced by Oxidative Coupling of Primary Aromatic Diamines

“…Other applications of oxidative coupling include the formation of carbon-carbon bonds between terminal acetylene groups giving either macrocyclic rings (4) or polymers (5)(6)(7), the polymerization of benzene to poly(pheny1ene) (8) and of bismercaptans to poly(disu1fides) (9). In addition, oxidative coupling is now being recognized as one of the major pathways in the biosynthesis of important natural products such a s lignin (19) and alkaloids (11).…”

Synthesis of a Morphinan Derivative by Oxidative Ring Closure

“…Chem., in press. [3] I thank Dr. R.Turn~nler, Dresden, for measurement of the electron-addition mass spectra. 141 R F = 0.44 on Kieselgel G (Merck), eluant CHC13/CH30H 9 : 1.…”

“…We now report the preparative synthesis of the morphinan derivative ( 9 ) by oxidative condensation of reticuline (3). Experience with oxidative condensations of other alkaloid precursors [31 indicates that in order to obtain higher yields it is necessary to prevent oxidative side reactions on the nitrogen, and intramolecular condensation and polymerization.…”

“…Morphinan derivatives could not be detected in the oxidation mixture by chromatographic investigation. The tertiary reticuline (3) was then oxidized by MnO;? in CHC13 using a heterogeneous variant of the Ziegler dilution principle.…”