Géza Timári

The first total synthesis of cicerfuran utilizing a one-pot synthesis of hydroxylated benzofurans

Abstract A simple one-pot procedure was elaborated for the preparation of hydroxylated benzofurans from halogenated phenols and was successfully applied to the first total synthesis of Cicerfuran, a natural defence agent of wild chickpea.

Synthesis of novel ellipticine analogues and their inhibition of Moloney leukaemia reverse transcriptase

Abstract Two new ellipticine analogues were synthetized as potential non nucleoside inhibitors of reverse transcriptase and were tested on Moloney leukaemia virus reverse transcriptase in vitro. Both derivatives (9a,b) showed considerable inhibitory effect; ID50 was found to be in the range of 2.8 to 4.5 × 10−5 M.

An Alternative Synthesis of Quindoline and one of its Closely Related Derivatives

Abstract The alkaloid Quindoline (13) and one of its tetracyclic isomer indazolo[2,3-a]quinoline (8) have been synthesised utilising the Pd(0)-catalysed cross-coupling reaction of pivaloylamino phenylboronic acid (2) with substituted quinolines.

Design and application of new imidazolylsulfonate-based benzyne precursor: an efficient triflate alternative.

Several o-(trimethylsilyl)aryl imidazolylsulfonates were synthesized in a simple process and successfully applied in cycloadditions involving benzyne intermediates. The precursor offers an efficient alternative for generating benzynes compared to widely used ortho TMS triflates under similar reaction conditions. With the utilization of this new precursor, the formation of potentially genotoxic trifluoromethanesulfonate side product is eliminated. The applicability of the new benzyne precursor was demonstrated in different types of cycloaddition reactions to prepare heterocyclic molecules.

Straightforward synthesis of 11H-indolo[3,2-c]isoquinoline and benzofuro[3,2-c]isoquinoline by ring transformation

Abstract An efficient method was established for the synthesis of 11 H -indolo[3,2- c ]isoquinoline and benzofuro[3,2- c ]isoquinoline using thermal ring transformation of a benzisoxazolo[2,3- a ]isoquinoline salt.

A CONCISE SYNTHESIS OF FUROSTIFOLINE

Abstract A five-step total synthesis of the furo[3,2- a ]carbazole alkaloid, furostifoline, was achieved using a Pd(0)-catalyzed cross-coupling reaction.

Stereoelectronic control in ring opening of bridge-head nitrogen containing fused azolium salts☆

Abstract Reaction of tetrazolopyridinium salts 1 with nucleophiles proceeds through the neutral intermediate 2. Ring opening of this leads to hetarylbutadienes (3,4,5) of different geometries. Experimental support has been provided for the theoretical supposition that 2 before opening up can undergo nitrogen inversion and the two invertomers of this intermediate (2A and 2B) react via the two possible senses of disrotation, one of them (2A) under stereoelectronic control. By this mechanism unexpected stereoselectivities are explained and the degree of selectivity can be predicted.

Theoretical interpretations of some experimental observations in reactions of triazolopyridines and their quaternary salts

Abstract The site of alkylation of triazolopyridines ( 1 a ), ( 5 ), and ( 6 ) has been interpreted using semi-empirical and ab initio molecular orbital calculations. Attack by hydride on the methyl triazolopyridinium salt ( 3a ) has been shown to give the triazolylbutadiene ( 4a ), while the isomeric salt ( 2a ) is unaffected by nucleophiles. These observations are interpreted by consideration of the mechanisms of reaction, and calculation of appropriate energy levels.

Ring opening of [1,2,3]triazolo[1,5-a]pyrazinium salts: Synthesis and some transformations of a novel type of 2-aza-1,3-butadienes

Abstract The synthesis of 1,3-disubstituted [1,2,3]triazolo[1,5-a]pyrazinium salts 6 and subsequent ring opening induced by the reaction with pyrrolidine provides a facile access to 4-(1-pyrrolidino)-1-([1,2,3]triazol-5-yl)-2-aza-1,3-butadienes 7, a new type of 2-aza-1,3-butadienes. Compounds 7 proved to be suitable starting materials for further ring formation reactions.

Cycloadditions with hetaryl dieneamines a direct route to hetarylazulenes

Hetaryl dieneamines readily available from fused N-aryl azolium salts with secondary amines were found to undergo cycloadditions. With N-phenylmaleinimide and acetylene dicarboxylic ester, [4+2] cycloaddition took place to yield tetrahydroisoindolone (2) and phtalic acid (3) derivatives, respectively. Reaction with fulvene reagent4 resulted in a [6+4] cycloaddition followed by a spontaneous elimination and allowed a convenient route to hetaryl azulenes (5–7).AbstractDie aus kondensierten N-Aryl-azoliumsalzen leicht zugänglichen Hetaryldienamine gehen Zykloadditionen ein. Mit N-Phenylmaleinimid und Acetylendicarbonsäureester traten [4+2]-Zykloadditionen ein, wobei Tetrahydroisoindolon- (2) und Phtalsäurederivate (3) erhalten wurden. Die Reaktion mit Fulvenreagenz4 führte zu einer [6+4]-Zykloaddition und anschlieβender spontaner Eliminierung; das erwies sich als eine bequeme Route zu Hetarylazulenen (5–7).