Lajos Szabo

Synthesis of vinca alkaloids and related compounds—XVI: New route to the stereoselective synthesis of (+)-vincamine, (-)-vincamone and (+)-apovincaminic acid esters

Abstract A stereoselective method has been elaborated for the synthesis of oxime esters, (-)-4a, b, from which, as common intermediates, (+)-apovincaminic acid esters (3a,b), (+)-vincamine (1) and (-)-vincamone (2) can be prepared.

Synthesis of vinca alkaloids and related compounds. LIII, A simple synthesis of (±)-3-oxovincadifformine and (±)-3-oxominovine

Starting from ethyl of 3- [5-ethyl-2-oxotetrahydro-1-pyridylethyl]indole-2-carboxylate synthese of the title compounds were achieved via linear reaction sequences

Synthesis of Vinca Alkaloids and Related Compounds, 76.1 Synthesis and Ring Transformations of Compounds with the Aspidospermane- and D-Noraspidospermane Skeleton. A Formal Synthesis Of (±)-12-Demethoxy-N(1)-Acetyl-Cylindrocarine

Abstract Reaction of compound (4) with (5) give a mixture of the isomers (7) and (8) through the intermediate (1). Further conversions led through the oxo- (9), (10) and thioxo (11), (12) derivatives to (±)-19-ethoxycarbonyl-19-demethylvincadifformine (3), and (±)-18-methoxycarbonyl-D(14)-norvincadifformine (13). The preparation of the former compound constitutes the formal synthesis of (±)-12-demethoxy-N(1)-acetylcylindrocarine (2). Oxidative ring transformation of the latter gave (±)-21-methoxycarbony 1-D(18)-norapovincamine (14).

Synthesis of Spiro-substituted Benzo[c]azepinones

Benzo[c]azepinones spiro-substituted by cyclohexanone, cyclohexenone and cyclohexadienone rings were synthesized from 2-tetralone via simple and convenient reaction steps.

Studies on stereoselective approaches to β-carboline derivatives

Transformation of β-carboline derivatives into optically active entities were studied and the de and ee values of the resulted compounds were detected.

Synthesis of vinca alkaloids and related compounds. Part 101: A new convergent synthetic pathway to build up the aspidospermane skeleton. Simple synthesis of 3-oxovincadifformine and 3-oxominovincine. Attempts to produce 15β-hydroxyvincadifformine

Abstract A molecule with an indole skeleton, containing a latent acrylic ester function—acting as a diene—was produced from Nb-trityl-2-(hydroxy-methyl)-tryptamine and reacted with esters containing an aldehyde or aldehyde-equivalent structural unit, yielding 3-oxo-16,17-dihydro-Δ20-secodin-17-ol type intermediates from which dehydration, followed by [4+2]cycloaddition, furnished 3-oxovincadifformine and 3-oxominovincine. We also wished to apply the method to produce 15β-hydroxyvincadifformine, however, the appearance of a dimeric product with indole skeleton was observed instead of the expected cycloaddition.

Bound and non-bound tetracyanoethylene radical anion (TCNE˙–) in copper(I) triphenylphosphine complexes. The crystal structures of Cu(TCNE)(PPh3)3, [-(CN)Cu(PPh3)2(TCNE)Cu(PPh3)2-]nand [(PPh3)3Cu(CN)Cu(PPh3)3][TCNE]

The reaction of the copper(II) complex [Cu(TCNE)]n with triphenylphosphine yields three different modes of incorporation of TCNE˙– into the products Cu(TCNE)(PPh3)31, [-(CN)Cu(PPh3)2(TCNE)Cu(PPh3)2-]n2 and [(PPh3)3Cu(CN)Cu(PPh3)3][TCNE]3. In 1, the TCNE˙– in 2, trans-N-bound TCNE˙– bridges alternate with CN bridges to produce a polymeric structure, and in 3 the TCNE˙– is un-coordinated.

Synthesis of vinca alkaloids and related compounds XLII: Transformation of vincamone into vincamines via diazomethane assisted homologization. application of 1h-noe measurements for the configurational as

Abstract The α-oxo-acids 4 and 5 derived from vincamone ( 1 ) were transformed into vicamines 2 , 8 , 10 ,respectively by methylene insertion with diazomethane. Homologisation of 3 and 6 dioxo compounds led to oxirane derivatives 8 , 16 , 11 , 13 , 13 , 18 , respectively. Configuration of the oxiranes was determined by 1H-NOE measurements.

Synthesis of vinca alkaloids and related compounds. Part 102: Simple synthesis and ring transformation of (±)-minovincine. First synthesis of (±)-vincaminine

Abstract A molecule with an indole skeleton, containing a latent acrylic ester function—acting as a diene—readily reacted with benzoic acid (4-bromomethylene-5-oxo)hexyl ester that had been built up from pentane-2,4-dione. Dehydration of the enamine and subsequent [4+2] cycloaddition supplied epimers having the d -secoaspidospermane skeleton. These compounds directly or after epimerization gave (±)-minovincine. Oxidative ring transformation of (±)-minovincine under different conditions led to (±)-16-acetyl-16-deethylapovincamine and (±)-vincaminine.

Synthesis of vinca alkaloids and related compounds. LXXVIII a potentially biologically useful reduction of nitro-vincristine

Abstract The nitration of the antitumor alkaloid Vincristine yields the non-toxic 7′-nitro derivative, which on reduction affords the original compound. The sequence has potential biological significance.