Gábor Blaskó

Studies aiming at the synthesis of morphine. II. Studies on phenolic coupling of N-norreticuline derivatives

Abstract The synthesis of salutaridine derivatives via phenolic coupling on norreticuline derivatives can be performed in improved yields, using non-metallic oxidizing agents. The assumption of a coordination effect in the preformation of the desired structure is, thus, unnecessary.

Conversion of a protopine into an indenobenzazepine. Stereoselective formation of cis- and trans-B/C fused indenobenzazepines

Treatment of the protopine (7) with strong base and sunlight yields the cis-fused indenobenzazepine (8) while reaction of the oxo-aziridine (9) with acidic reagents leads to the trans-indenobenzazepines (13), (15), and (17), which isomerize with time in the reaction medium to the corresponding cis-analogues (14), (16), and (18).

Phthalideisoquinoline enol lactones

Abstract :(Z)-Narceine enol lactone ( 10 ) is thennodynamically less stable than its geometric isomer 11 , and solvolyses faster in methanol to provide keto ester 9 . In the less hindered hydrastine series, however, the order is reversed, and it is the E isoner 4 which is less stable than the Z analog 3 and which solvolyses faster to keto ester 6 .

Chapter 1 Reissert Synthesis of Isoquinoline and Indole Alkaloids

Publisher Summary This chapter describes the preparation and reaction of Reissert compounds, synthesis of isoquinoline alkaloids, and synthesis of indole alkaloid analogs. The most frequently used method for the preparation of isoquinoline Reissert compounds is treatment of an isoquinoline with acyl chloride and potassium cyanide in water or in a dichloromethane–water solvent system. Although, this method can be successfully applied in a great number of syntheses, it has also some disadvantages. Acid-catalyzed hydrolysis of Reissert compounds results in an aldehyde, a formal reduction product of the acyl halide utilized in the Reissert compound formation. The synthetic approach via Reissert compounds proves to be one of the most efficient routes to the alkaloids. More recently, the synthesis of aporphines, phthalideisoquinolines, and ellipticines, all of them possessing different valuable pharmacological properties, have become the target of organic chemists. The Reissert approach has proved to be a good synthetic tool with general applicability to the synthesis of these types of alkaloids.

Chapter 2 Corynantheine, Yohimbine, and Related Alkaloids

Publisher Summary This chapter describes the corynantheine–yohimbine group of monoterpene indole alkaloids with greater emphasis on their chemistry including structural elucidations, synthesis, transformations, reactions, spectroscopy, and pharmacology. The simplest member of the indolo[2,3-a]quinolizine alkaloid group has been found in Dracontomelum magniferum B1; it possesses structure (−)-1. The structures of vincarpine and dihydrovincarpine are determined on the basis of their spectral data and via some derivatives obtained by either catalytic or hydride reduction. Pharmacological investigation of a great number of C- 18-acyloxy analogs of reserpine showed that alteration at this site of the molecule exerts smaller or greater modification of the original activity. In comparison with other spectroscopic methods, 13 C-NMR spectroscopy affords the most valuable information for the stereochemical and conformational analysis of quinolizidine compounds. Among naturally occurring compounds the indole alkaloids play important roles as biologically active substances. Yohimbine is a sympathicolytic agent, and yohimbine and its naturally occurring diastereomers can be used as valuable tools for the subclassification of α-adrenoceptors, including the differentiation between the high and low affinity sites.