Yiannis Elemes

Synthesis of sulfur containing dihydro-pyrrolo derivatives and their biological evaluation as antioxidants.

The 1,3-dipolar cycloaddition to N-phenylmaleimide of azomethine ylides, generated in situ from sulfanyl-substituted imines of glycine esters, yields 5H-dihydro-pyrrolo products with syn diastereoselectivity. The syn (major) and anti (minor) products were isolated chromatographically and fully characterized by spectroscopic methods and in two cases also by X-ray analysis. The diastereomeric cycloadducts were tested for their antioxidant activity with good results.

An Interplay in the Regioselectivity Induced by Non Bonding Interactions, in the ene Reactions of Singlet Oxygen and Triazolinediones with Tetrasubstituted Alkenes

The ene reactions of N-phenyl-1,2,4-triazoline-3,5-dione (PTAD) and singlet oxygen (1O2) with tetrasubstituted alkenes, follow regioselectivity trends governed mainly by 1,3-non bonded interactions (type I) for the case of PTAD, and mainly by the steric hindrance caused during the formation of the new double bond (type II) for the case of 1O2. The results are explained in terms of a “late” product forming transition state of hydrogen abstraction for triazolinediones and an “early” transition state for the analogous singlet oxygen reaction.

The Question of Electrophilic vs Nucleophilic Addition of Cyclic β-Dicarbonyl Phenyliodonium Ylides: Electrophilic Cycloaddition of Diphenylketene

The reaction of β-dicarbonyl phenyliodonium ylides with diphenylketene at room temperature affords mixtures of lactone and aurone derivatives. The initial electrophilic attack of the iodonium ylide on the C(β) position of the diphenylketene, followed by cyclization of the zwitterionic species, and subsequent ejection of iodobenzene, affords the lactone and aurone cycloadducts. Treatment of β-dicarbonyl iodonium ylides with acyl chlorides yields α-chloroenones with good to excellent yields.

Synthesis of Novel 3,4‐Dihydro‐2H‐pyrrolo[60]fullerene Derivatives Bearing an Alkylsulfanyl Substituent

Abstract C60 reacts thermally with azomethine ylides of glycine imines, in methyl ester and free acid form, bearing two alkylsulfanyl groups to give dihydro‐pyrrolo[60]fullerene derivatives 2 and 5a, respectively, in a 1,3‐dipolar cycloaddition reaction. The yields of products were found to depend strongly on acidic conditions applied and the size of the alkylsulfanyl substituent.

Erratum to: Laboratory evaluation of five novel pyrrole derivatives as grain protectants against Tribolium confusum and Ephestia kuehniella larvae

Several naturally discovered or laboratory-synthesized pyrrole compounds have insecticidal, acaricidal and microbial properties. The novel sulfanyl 5H-dihydro-pyrrole derivatives exhibit certain antioxidant activities. However, there is a knowledge gap whether these substances are potent grain protectants against stored-product insect pest species. In this context, we evaluated the insecticidal activity of five novel pyrrole derivatives (under the trivial names 3a, 3g, 3l, 3m, 3h), against larvae of Tribolium confusum Jaquelin du Val and Ephestia kuehniella Zeller at different doses (0.1, 1 and 10 ppm), exposure intervals (7, 14 and 21 days or 1, 2, 7, 14, 21 days), temperatures (20, 25 and 30 °C), relative humidity (RH) (55 and 75 %) levels and commodities (wheat, maize, barley). The pyrrole derivative 3a exhibited the highest insecticidal activity, while 3g, 3l, 3m and 3h caused similar mortality against larvae of T. confusum. Apart of the level of efficacy, all tested pyrrole derivatives performed similarly according temperature. We found that increase in temperature increased mortality in the majority of the tested combinations. Generally, the pyrrole derivatives caused the highest mortality levels at 30 °C. The pyrrole derivatives 3a, 3g, 3l and 3m were affected by relative humidity at almost all combinations tested. The 75 % level of RH moderated the efficacy of the pyrrole derivatives, while the 55 % enhanced it. Mortality of T. confusum and E. kuehniella on maize was much lower on treated maize than barley or wheat. However, 100 % control of both species was recorded only on treated barley. The results of the present study indicate that the pyrrole derivatives tested could serve as grain protectants against noxious stored-product insects under certain biotic and abiotic conditions.

Eco-friendly synthesis of novel thiohydantoin-type sulfur-containing imidazolinone derivatives from glycine ester

Imino derivatives of glycine ester were prepared from methyl glycinate by the known procedure and then they reacted with several amines under microwave irradiation without solvent that gave the corresponding glycine amides. By the one-component cyclocondensation, the obtained amide derivatives were transformed into thiohydantoin-type imidazolinones using solvent-free microwave procedure. All imine-ester derivatives and most of the imidazolinone derivatives were synthesized for the first time. This eco-friendly protocol can provide a suitable way for synthesizing new potentially bioactive imidazolinone derivatives.

Synthesis of PhTAD-substituted dihydropyrrole derivatives via stereospecific C–H amination

Stereospecific α-amination has been accomplished via addition of N-phenyltriazolinedione (PhTAD) to the allylic position of dihydropyrroles. The aim of this study is to evaluate new PhTAD derivatives of biologically active bicyclic dihydropyrroles. Ene reaction was accomplished via addition of PhTAD to the allylic position to react with syn and anti diastereomers for α-amination. The α-amination depends on the stereochemistry, proceeding faster with syn than anti diastereoisomers. Steric hindrance from sulfide substituent slows down the transformation. Although the results are in accordance with an ene reaction followed by 1,3-shift of the urazole moiety, deuteration at the allylic position by simply stirring the diastereoisomeric dihydropyrroles in MeOD revealed a [1,3-H] shift. The stereospecificity of the transformation is attributed to steric hindrance during the allylic transposition step.

CCDC 1435966: Experimental Crystal Structure Determination

Related Article: Emel Pelit, Kosmas Oikonomou, Melek Gul, Dimitra Georgiou, Slawomir Szafert, Sotirios Katsamakas, Dimitra Hadjipavlou-Litina, Yiannis Elemes|2017|Comptes Rendus Chimie|20|424|doi:10.1016/j.crci.2016.05.024

Hydrated forms of N-[(3R)-3-(4-methyl-3,5-dioxo-1,2,4-triazolidin-1-yl)-2-methyl­ene­butano­yl]-(1S,2R)-bornane-10,2-sultam and its enanti­omer

Triazolidinediones react with each enantiomeric bornanesultam derivative of tiglic acid to produce the appropriate ene adduct in high yield and with excellent regioselectivity and diastereoselectivity. The optically pure products, viz. N-[(3R)-3-(4methyl-3,5-dioxo-1,2,4-triazolidin-1-yl)-2-methylenebutanoyl](1S,2R)-bornane-10,2-sultam 0.15-hydrate, C18H26N4O5S 0.15H2O, and its enantiomer N-[(3S)-3-(4-methyl-3,5-dioxo1,2,4-triazolidin-1-yl)-2-methylenebutanoyl]-(1R,2S)-bornane10,2-sultam 0.35-hydrate, C18H26N4O5S 0.35H2O, have been characterized by spectroscopy and single-crystal X-ray analysis. Their structures are the result of C -re attack of the enophile on the double bond of the alkene.