István Moldvai

A practical route to epibatidine

Abstract A practical synthetic approach to the alkaloid Epibatidine has been developed. This method is convenient and easy to scale up.

A PRACTICAL ENANTIOSELECTIVE SYNTHESIS OF EPIBATIDINE

Abstract Two different syntheses of Epibatidine ( 1 ) were designed and carried out using easily accessible reagents and convenient reaction conditions. The ring closure of the prochiral precursor 4 catalyzed by optically active α-phenyl-ethyl-amine gave the key intermediate 5 in over 80% ee from which the natural product (−)- 1 has been prepared.

Synthesis of vinca alkaloids and related compounds LX. A simple transformation of apovincamine into vincamine

Abstract The 15α-chloro-vincamine derivative 2 was prepared and proved to be key intermediate of a two-step transformation of apovincamine into vincamine. The structure of 2 was established via detailed NMR and X-ray investigations.

Synthesis of vinca alkaloids and related compounds XXXI unusual polonovski reaction of some vinca alkaloids

Abstract In the course of the Polonovski reaction of some indole alkaloids a new type of dimerization has been found.

Validation of high-affinity binding sites for succinic acid through distinguishable binding of gamma-hydroxybutyric acid receptor-specific NCS 382 antipodes

Gamma-hydroxybutyric acid (GHB) binding to multiple sites for the tricarboxylic acid cycle intermediate succinic acid (SUC) has been disclosed recently. In order to better characterize these targets, distinguishable binding of GHB receptor-specific NCS 382 antipodes to [(3)H]-SUC or [(3)H]-GHB labelled sites in rat brain synaptic membranes was explored. Eutomer binding parameters suggest identity of the high-affinity target for SUC with a synaptic GHB receptor subtype.

New routes to clavine-type ergot alkaloids. Part 1. First total synthesis of three natural products : (+)- setoclavine, (+)-isosetoclavine, (-)-9,10-dihydroisosetoclavine, and structure correction of the latter

The double bond in ring D of (+)-9,10-didehydro-6-methylergolin-8-one (2) was reduced selectively by catalytic hydrogenation to yield (-)-6-methylergolin-8-one (6). Grignard reaction of 6 has been performed with methylmagnesium iodide to afford two isomers (5 and 7). The main isomer having an 8a-methyl group at C8 with a C/D-trans junction (5; (-)-dihydroisosetoclavine) proved to be identical with the natural product, hence its name and structure should be corrected. As a minor isomer (7) a C/D-cis clavine derivative was also isolated which can be regarded as unnatural (+)-8α-hydroxy-costaclavine. (+)-Setoclavine (8) and (+)-isosetoclavine (9) have also been prepared from 2, thus achieving the first total synthesis of these natural products. Detailed structure elucidation of 5-9 has been carried out as well.

Synthesis of vinca alkaloids and related compounds LXXVII. Dimers of criocerine

Abstract Criocerine analogues of type 3 , when dissolved in acetic acid, form the novel dimeric compounds of type 6 whose structures were thoroughly investigated by NMR spectroscopic methods.

Chemistry of indoles carrying a basic function. Part 8: A new approach to the ergoline skeleton

Starting from N-pivaloyl-Uhles ketone a new synthetic approach to the ergoline skeleton has been elaborated. Ring D of the tetracyclic skeleton was formed by an intramolecular Dieckmann-condensation of a diester, obtained in a Reformatsky reaction of a properly substituted derivative of N-pivaloyl Uhles ketone followed by elimination of water.

Synthesis of Vinca Alkaloids and Related Compounds. PART LVIII. A Novel Formal Synthesis of (−)-Criocerine from (+)-Vincamine

Abstract 18-lodo criocerine (3), a synthetic precursor to (−)-criocerine (1), was prepared from (+)-vincamine (4) via a new one-step procedure. Full 1H and 13C NMR assignments for 3 are also given.

Formation and mechanistic implication of a novel thiaazabicyclooctane derivative drug the cycloaddition of n-acetyl cinnamic acid thioamide

Abstract In the course of synthesizing thiopyran 3a, the novel thiaazabicyclooctane derivative 8, a precursor to 3a, has been isolated as a major product. The formation of 8 provides further insight into the mechanism of the [4+ 2] cycloaddition involving 1a, which we have previously discussed to be an efficient way of generating usefully functionalised dihydrothiopyrans. The structure of compound 8 was established by detailed NMR investigations.