Elena Stanoeva

Cyclocondensations of homophthalic anhydrides with 1-aza-1,3-dienes

Abstract α,β-Unsaturated aldimines (1-aza-1,3-butadienes) 2, 4 and 7a-d react with homophthalic anhydrides 1a,b to give 3,4-dihydro-1(2H)-naphthalenone-4-carboxylic acids 3, 5, 8a-d (R2 = H) as main products. Homophthalic anhydride 1a and cinnamaldimine 7d gave rise to the diastereoisomeric naphthalenones 8d (R2 = H), along with the 3,4-dihydro-1(2H)-isoquinolinone-4-carboxylic acids 10 (R2 = H), and 3,4-dihydro-1(2H)-pyridinone 11 (R2 = H) as products of 3,4-, 1,2- and 1,4-addition to the 1-aza-1,3-butadiene, respectively. The effect of the reaction conditions on the ratio of adducts, produced by 1a and 7d, was studied. The structure and relative configurations of 3, 5, 8a-d, 10 and 11 were determined by NMR spectroscopy. In the case of cis-naphthalenone 8c and dihydropyridinone 11, the structure was confirmed by X-ray crystal structure analysis.

Synthesis of α-diones and α-diimines by regioselective α-alkylation of 2,3-alkanediimines

Abstract While α-diones are not easily alkylated at the α-position via their enolates, the corresponding α-diimines can be alkylated conveniently to afford higher homologues, which are easily hydrolyzed into homologous α-diones.

Synthesis and spectroscopic properties of new Schiff bases containing the N-phenylaza-15-crown-5 moiety

Abstract A series of two Schiff bases, 1 and 2 , containing the N -phenylaza-15-crown-5 moiety was prepared by condensation of the formyl- and amino derivatives of N -phenylaza-15-crown-5 ( 3 ) with p -substituted anilines and benzaldehydes respectively. The starting macrocycle 3 was synthesized via a new modified procedure. UV- and 1 H-NMR spectral data of 1 and 2 are given.

Reactions of α-chloroimines with homophthalic anhydrides. Synthesis and molecular structure of 3,3a-dihydrofuro[3,4-c] isoquinoline-1,5(4h,9bh)-diones, furo[3′, 4′:9,9α]-8,9,16,16a-tetrahydro-1h,3h,11h-dibenzo[a,g]quinolizine-1,11-diones and related compounds

Abstract The reaction of α-chloroimines 1 - 3 , resp. 11 with homophthalic anhydrides 4 leads to the formation of the isoguinoline ring system incorporated in furo[3,4-c]isoquinolinediones 8 - 10 , resp. 13a-(chloromethyl)-8H- dibenzo[a,g]-quinolizine-8-one-13-carboxylic acids 12 . The latter compounds were converted into furo[3′ 4′:9,9a]dibenzoquinolizinediones 13 under basic conditions. NMR studies provided information concerning the relative configuration and the solution conformation of the various heterocycles obtained. The molecular structure of 8b and 12b was determined by X-ray analysis.

Synthesis and Plant Growth Regulating Activity of New Triazolo- and Pyrazolopyrimidine Derivatives Of Aminomethyl, Aminoalkyloxymethyl Dimethylphosphine Oxides and (Aminomethane)Phosphonic Acid Esters

Abstract New triazolo[4,5-d]pyrimidine and pyrazolo[3,4-d]pyrimidine derivatives of aminomethyl-and aminomethyloxymethyl dimethylphosphine oxides 8–14 as well as of esters of (aminomethane) phosphonic acid 18–20 were synthesized. The structure of the compounds prepared was confirmed by means of elemend analysis, IR, 1H- and 31P(1H)-NMR spectroscopy. Tertiary phosphine oxides 8, 9 and 12 as well as phosphonate 20 showed herbicidal and plant growth regulating activity.

Synthesis of 11H-4b, 10b-dihydro [1] benzopyrano [4,3-c] isoquinoline-6,11 (5H)-diones and 13H-6c, 12b-dihydronaphtho [1′,2′:5,6]-pyrano [4-3c] isoquinoline-8,13 (7H)-dione from homophthalic anhydride and N-(2-hydroxyarylidene) alkylamines

Abstract 2-Alkyl-3-(2-hydroxyaryl)-3,4-dihydro-1(2H)-isoquinolinone-4-carboxylic acids (5,13) were prepared from homophthalic anhydride (1) and N-(2-hydroxyarylidene) alkylamines (2,10). The acids 5,13 showed a tendency towards cyclodehydration to give isoquinoline derivatives with fused [1] benzopyrane (8) or naphthopyrane (12) ring system. The relative configurations of the novel fused heterocyclic compounds 5,8,12,13 and related compounds were determined by NMR studies, and in the case of 13 also by means of X-ray analysis. Some MM2 force field molecular mechanics calculations on some selected fused heterocycles were executed. The naphtho [1′,2′:5,6] pyrano [4,3c]-isoquinoline ring system incorporated in the lactone 12 is hitherto unreported.

Complexation Properties of Schiff Bases Containing the N-Phenylaza-15-crown-5 Moiety

The complexation of a series of new Schiff bases containing theN-phenylaza-15-crown-5 (Ph-A15C5) moiety with alkali and alkaline-earth metal ions (incl. Be2+ and Mg2+, is studied by means of UV-Vis spectroscopy. The corresponding stability constant values are determined and discussed from two aspects: the position of the Ph-A15C5 moiety in the ligand molecule and the nature of the metal ion.

Synthetic Approaches toward the Benzo[a]quinolizidine System. A Review

Introduction ...........................................................................................426 I. Formation of Ring B ...............................................................................429 1. Bischler-Napieralski Reaction ...........................................................429 2. Pomeranz–Fritsch Reaction ...............................................................431 3. Pictet-Spengler Reaction ...................................................................433 4. Intramolecular Heck Reaction ...........................................................438 5. Photochemical Cyclization ................................................................440 6. Parham Cyclization ..........................................................................440 II. Formation of Ring C................................................................................442 1. Dieckmann Condensation..................................................................442 2. Intramolecular Aminolysis ................................................................444 3. Aza-annulation Reactions..................................................................447 4. Other Cycloaddition Reactions...........................................................456 5. viaMulticomponent Reactions ...........................................................457 6. via Alkene Metathesis.......................................................................458 7. Protoberberine Ring D Degradation ....................................................460 8. Synthesis of 8-Azasteroids.................................................................461 9. Radical Cyclization ..........................................................................462 Conclusion ..............................................................................................462 References ..............................................................................................463

Influence of cytokinins and novel cytokinin antagonists on the senescence of detached leaves of Arabidopsis thaliana

Cytokinins N6-benzyladenine (BA) and 1-(2-chloropyridin-4-yl)-3-phenylurea (4PU-30) delayed the senescence of detached leaves (3rd to 7th leaf node) of wild and ethylene insensitive eti5 mutant of Arabidopsis thaliana. The novel anticytokinins, structural analogues of purine and phenylurea cytokinins also affected the senescence of detached rosette leaves of A. thaliana. They diminished to a significant extent the cytokinin-induced delay of chlorophyll destruction, but without a considerable difference in their action against both types of cytokinins. These results correlated with changes observed in ribonuclease (RNase) activity.

Antagonistic effects of triazolo[4,5-d]pyrimidine and pyridylurea derivatives on cytokinin-induced cytokinin oxidase/dehydrogenase activity in young pea plants

The effect of strong and weak cytokinin antagonists, belonging to the groups of triazolo[4,5-d]pyrimidines (TP), and pyridyl-phenylurea derivatives (PU), on cytokinin oxidase/dehydrogenase activity (CKX) in the tissues of young pea plants was studied. Tested anticytokinins, with the exception of the most efficient one – PU-1, were able to promote increased CKX activity in roots, when applied alone, but they had no significant influence on the enzymatic activity in leaves. N6-benzyladenine (BA) and 1-(2-chloropyridin-4-yl)-3-phenylurea (CPPU) provoked strong increase in CKX activity in roots, while in leaves considerable inhibition of enzymatic activity was observed. Different types of anticytokinins exhibited diverse preference towards taking off the action of purine and phenylurea cytokinins over CKX activity.