Mária Incze

Synthesis of vinca alkaloids and related compounds. LXII: Synthesis of desmethoxy “decarbomethoxy apocuanzine”

Starting from the intermediate product (5) of the desmethoxy cuanzine synthesis, (±)-desmethoxy “decarbomethoxy apocuanzine” (4) was synthesized.

Synthesis of vinca alkaloids and related compounds LV synthesis of (±)-desmethoxy cuanzine

Abstract Through the key intermediate enamine ( 28 ) (±)-desmethoxy cuanzine ( 2 ) was synthesised.

CO2 inclusion bands in i.r. spectra of KBr pellets

Abstract Experimental data are given suggesting that i.r. bands arising from chemical transformation of an organic compound in potassium bromide pellets are due to occluded carbon dioxide having no rotational degrees of freedom.

SYNTHESIS OF VINCA ALKALOIDS AND RELATED COMPOUNDS. LXV: PREPARATION OF 7-METHOXYTRYPTAMINE

Abstract 7-Methoxytryptamine (6a) was prepared from cheap and easily available starting materials by using the Abramovitch-Shapiro method.

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.

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, LXXI : Synthesis of (±)-cuanzine, (±)-decarbomethoxyapocuanzine, and some of their epimers

Abstract Starting from 7-methoxytryptamine (7) with the use of the method we developed earlier, (±)-cuanzine (1),(±)-decarbomethoxyapocuanzine (4), and their epimers 5 and 22 were synthesized.

Synthesis of vinca alkaloids and related compounds XXVII formation of a stable 3-acylindolenine☆

Abstract A stable 3-acylindolenine derivative (2) has been prepared via intramolecular electrophilic acylation. The reactivity of 2 has been studied.

Cyclopropanation of carbon-carbon double bonds in ring d of ergot alkaloids

Some ergot alkaloid derivatives containing a double bond in ring D have been reacted with diazomethane/palladium diacetate reagent to result in formation of a fused cyclopropane ring. This procedure proved to be generally applicable for cyclopropanation of Ergot alkaloids.

Chemistry of indoles carrying a basic function. Part IX. Unexpected cyclizations of diketones derived from Uhle's ketone

Starting from a tricyclic diketone (14) obtained by Bowmans method, a tetracyclic oxonaphthalene derivative (17) has been prepared through intramolecular aldol condensation followed by indole → naphthalene isomerization. An unexpected formation of a lactol ether (16) was observed as a result of acidic treatment of 14. Two modified reaction sequences starting from N- methyl derivatives have also been presented. The keto ketal (26) gave a macrocyclic lactol (27) with unexpected structure as a result of deketalization with trimethylsilyl iodide. The formation of a tetracyclic lactam (37) was observed while applying the modified Reformatsky reaction to ketone (33).