bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methylated DNA: The influence of 7‐deaza‐7‐methylguanine on the structure and stability of oligonucleotides
Authors: Seela Frank , Chen Yaoming 
Published: December 2004

AbstractThe 7‐deaza‐2′‐deoxy‐7‐methylguanosine (2b) [9], which is the glycosylic‐bond‐stable, noncharged analogue of 2′‐deoxy‐7‐methylguanosine (1b), was incorporated in DNA by solid‐phase synthesis. As building blocks, the protected phosphonatc 3a and the phosphoramidite 3b were prepared. The 7‐methyl group of 2b stabilizes the B‐DNA duplex compared to 7‐deaza‐2′‐deoxyguanosine but does not induce a B‐Z transition as it is known from compound 1b. The stabilization by the 7‐deaza‐7‐methylguanine moiety is sequence‐dependent, and the nearest‐neighbor influence is different from that of 7‐deazaguanine. Homooligonucleotides of 2b show sigmoidal melting indicating a highly ordered single‐stranded structure. In general, Oligonucleotides containing 2b are very stable against hydrolysis with calf‐spleen phosphodiesterase (CS‐PDE, 5′ → 3′ exonuclease), while phosphodiester hydrolysis with snake‐venom phosphodiesterase (SV‐PDE, 3′ → 5′ exonuclease) is only slightly reduced.
Iridoid Glucosides with Free Radical Scavenging Properties from Fagraea blumei
Authors: Cuendet Muriel , Hostettmann Kurt , Potterat Olivier , Dyatmiko Wahjo 
Published: December 2004

AbstractFour new iridoid glucosides 1–4, named blumeosides A–D, were isolated from the methanolic stem‐bark extract of Fagraea blumei G. DON. (Loganiaceae). They were accompanied by the benzyl‐alcohol derivative di‐O‐methylcrenatin (5) and the flavone C‐glucoside swertisin (6). The structures of 1–4 were established by spectroscopic methods, including FAB‐MS, and 1H‐ and 13C‐NMR, and by alkaline hydrolysis. Blumeosides A (1) and C (3) are 10‐O‐(2,5‐dihydroxytercphthalo) adoxosidic acid and 10‐O‐(2‐hydroxyterephthalo)adoxosidic acid, respectively. In blumeosides B (4) and D (2), both carboxylic groups of the terephthalic‐acid moiety are esterified by adoxosidic‐acid units, Blumeosides A–D (1–4) inhibited bleaching of crocin induced by alkoxyl radicals. Blumeosides A (1) and D (2) also demonstrated scavenging properties towards the 2,2‐diphenyl‐1‐picryl‐hvdrazvl (CDPPH) radical in TLC autographic and spectrophotometric assays.
Introduction of Amino Alcohols in the Ring‐Opening Reaction of 3‐bromo‐2,5‐dimethylthiophene 1,1‐dioxide. A short diastereoselective synthesis of substituted ‘tetrahydrobenzo[a]pyrrolizidines’ (= octahydro‐1H‐pyrrolo[2,1‐a]isoindoles) using L‐prolinol
Authors: Tsirk Anders , Gronowitz Salo , Hörnfeldt Anna‐Britta 
Published: December 2004

AbstractTetrahydrobenzo[a]pyrrolizidines (= octahydro‐1H‐pyrrolo[2,1‐a]isoindoles) and tetrahydrobenzo[a]indo‐lizidines, (= decahydropyrido[2,1‐a]isoindoles) were prepared stereoselectively in four steps through an amineinduced ring‐opening of 3‐bromo‐2,5‐dimethylthiophene 1,1‐dioxide (1) with L‐prolinol (9), piperidine‐2‐methanol (10), and piperidine‐2‐ethanol (11), yielding the dienes (2S)‐1‐[(2E,4Z)‐4‐bromohexa‐2,4‐dienyl]pyrrolidine‐2‐methanol (12), 1‐[(2E,4Z)‐4‐bromohexa‐2,4‐dienyl]piperidine‐2‐methanol (13), and 1‐[(2E,4Z)‐4‐bromo‐hexa‐2,4‐dienyl]piperidine‐2‐ethanol (14; Scheme2), which, after conversion into their α,β‐unsaturated esters, cyclized in a TiCl4‐catalyzed intramolecular Diets‐Alder reaction (Scheme3). A discussion on the mechanism of the ring opening reaction including semiempirical and ab initio calculations is also presented.
X‐Ray Structure Analyses of Alkyl‐Substituted N‐Acryloyl‐ and N‐Crotonoyltoluenesultams
Authors: Bernardinelli Gérald , Chapuis Christian , Kingma Arend J. , Wills Martin 
Published: December 2004

AbstractThe X‐ray crystal‐structure analyses of two N‐enoyl‐toluenesultam derivatives 1 are reported. The structural differences with their bornanesultam analogues 2 as well as stereochemical aspects with respect to their [4 + 2] and [3 + 2] cycloadditions are discussed.
Theoretical Parameters to Characterize Antioxidants. Part 1. The case of vitamin E and analogs
Authors: Migliavacca Eugenia , Carrupt Pierre‐Alain , Testa Bernard 
Published: December 2004

AbstractThe objectives of ibis work were (a) to evaluate parameters obtained by quantum‐mechanical calculations as predictors of antioxidant activities, and (b) to obtain information on the molecular mechanism(s) underlying the antioxidant effects of vitamin E and analogs. To this effect, we selected a large series of tocopherol analogs for which some experimental antioxidant activities were available in the literature (i. e., peak of oxidation potential, Ep, and rate constant of the reaction with a free radical log ks). AM1 Semi‐empirical calculations were performed, the results of which were validated by ab initio calculations on a subset of compounds. The quantum chemical descriptors considered here (HOMO, ΔHox and ΔHabs) were fairly well correlated with the experimental antioxidant activities (Ep and ks). Moreover, these theoretical parameters were intercorrelated, suggesting that vitamin E analogs may act by a dual mechanism of single‐electron transfer (SET) and direct H‐atom abstraction.
7‐Deazaguanine DNA: Oligonucleotides with hydrophobic or cationic side chains
Authors: Ramzaeva Natalya , Mittelbach Cathrin , Seela Frank 
Published: December 2004

AbstractThe phosphoramidites 6b and 9 as well as the phosphonate 6a derived from 7‐(hex‐1‐ynyl)‐ and 7‐[5‐(trifluoroacetamido)pent‐1‐ynyl]‐substituted 7‐deaza‐2′‐deoxyguanosines 1 and 10, respectively, were prepared (Scheme 1). They were employed in solid‐phase oligodeoxynucleotide synthesis of the alternating octamers d(hxy7c7G‐C)4 (12), d(C‐hxy7c7G)4 (13), and d(npey 7c7G‐C)4 (15) as well as of other oligonucleotides (see 22–25; Table 2; hxy = hex‐1‐ynyl, npey = 5‐aminopent‐1‐ynyl). The Tm values and the thermodynamic data of duplex formation were determined and correlated with the major‐groove modification of the DNA fragments. A hexynyl side chain introduced into the 7‐position of a 7‐deazaguanine residue (see 1) was found to fit into the major groove without any protrusion. The incorporation of the (5‐aminopent‐1‐ynyl)‐modified 7‐deaza‐2′‐deoxyguanosine 2 into single‐stranded oligomers of the type 24 and 25 did not lead to change in duplex stability compared to the parent oligonucleotides. The self‐complementary oligomer 15 with alternating npey7c7Gd (2) and dC units did not lead to a cooperative melting, either due to orientational disorder or interaction of the 5‐aminopent‐1‐ynyl moiety with a base or with phosphate residues nearby or on the opposite strand.
Boophiline, an antimicrobial sterol amide from the cattle tick boophilus microplus
Authors: Potterat Olivier , Hostettmann Kurt , Höltzel Alexandra , Jung GüNther , Diehl Peter‐Allan , Petrini Orlando 
Published: December 2004

AbstractBoophiline (1), a new sterol amide was isolated from the cattle tick Boophilus microplus (Ixodidae). The structure was assigned as N‐[3‐(sulfooxy)‐25ξcholest‐5‐en‐26‐oyl]‐L‐isoleucine by detailed 2D NMR investigations in conjunction with FAB mass spectrometry and acidic hydrolyses. Complete assignment of the diastereotopic methylene protons of the ring system could be deduced from the NMR data. In agar dilution assays, 1 exhibited antifungal properties against Cladosporium cucumerinum and antibacterial activity against Bacillus subtilis and Escherichia coli.
Total synthesis of 2,6‐dimethylergolin‐8α‐amines
Authors: Waldvogel Erwin , Engeli Peter , Küsters Ernst 
Published: December 2004

AbstractA stereoselective total synthesis of the racemic form of the 2,6‐dimethylergolin‐8ã‐amine derivative III, previously obtained semi‐synthetically from lysergic acid, is described. Starting from the commercially available tricyclic lactam 1, the 9,10‐didehydroergoline skeleton containing an angular Me group in position 3 (see 18) is built up in several steps applying a Woodward D‐ring annelation sequence. The introduction of the 8‐amino group is achieved with complete diastereoselectivity to give exclusively the 8ã‐derivative 22. Subsequently, a Wagner‐Meerwein‐type migration of the angular Me group yields the 2‐methylated 9,10‐didehydroergoline derivative 31. The feasibility of this key transformation was tested on the two model systems 4 and 7 prior to the evaluation of the total synthesis. A stereoselective Birch reduction to the trans‐fused ergoline, and deacetylation/acylation conclude the total synthesis of the racemic target compound 34.In addition, the resolution of an early intermediate (see 3) by chromatography on a chiral stationary phase is presented which demonstrates that the described total synthesis could also be used for the preparation of the biologically active (5R,8S,10R)‐enantiomer III.
The enantioselective copolymerisation of allylbenzene, 1‐allyl‐4‐(trifluoromethyl)benzene, and 1‐allyl‐4‐methoxybenzene with carbon monoxide
Authors: Benedetto Silvia Di , Consiglio Giambattista 
Published: December 2004

AbstractThe olefins mentioned in the title were copolymerized with CO in the presence of palladium catalysts modified with dicyclohexyl{(R)‐1‐[(S)‐2‐(diphenylphosphino)ferrocenyl]ethyl}phosphine. Productivities up to 95 g/(gPd · h) were achieved. The obtained copolymers were recovered in the pure, regio‐ und stereoregular polyketone structures3. The isotactic poly[2‐benzyl‐1‐oxopropane‐1,3‐diyl] (3a) and its analogues 3b, c were found to isomerize to the corresponding spirocyclic poly[3‐(arylmethyl)tetrahydrofuran‐2,2‐5,5‐tetrayl‐2‐oxy‐2‐methylene]s 4 in a suspension in CHC13, thus indicating that the spiroketal structure is thermodynamically the most stable for these copolymers. However, the atactic material did not undergo any structural transformation. These results show that regularity at the centers of chirality in the main chain is a prerequisite for the conversion of the polyketone to the spiroketal structure.
Potassium Cryptate of a Macrobicyclic Ligand Featuring a Reducible hexakis(phenylthio)benzene electron‐acceptor site
Authors: Mayor Marcel , Lehn Jean‐Marie 
Published: December 2004

AbstractThe synthesis and structural characterization of the macrobicyclic ligand 1 containing a reducible hexakis‐(phenylthio)benzene electron‐acceptor site is described. It is based on the condensation of the tetraoxa‐diazamacrocycle 3 with a suitably functionalized derivative 4 of hexakis(phenylthio)benzene. Complexation of a potassium cation by 1 gives the corresponding cryptate 2, with a stability constant of ca. 4000 M−1 as determined by 1H‐NMR titration in CD3CN. The reduction potential of the hexakis(phenylthio)benzene electron‐acceptor site in 2 is shifted by 170 mV towards more positive values with respect to that in 1 by complexation of potassium.
Push‐Pull Butadienes: Evidence for a possible CH…︁S hydrogen bond in 4‐(methylthio)‐4‐nitro‐1‐(pyrrolidin‐1‐yl)buta‐1,3‐diene
Authors: Surange Sheetal S. , Kumaran Govindaraj , Rajappa Srinivasachari , Pal Debnath , Chakrabarti Pinak 
Published: December 2004

AbstractX‐Ray crystal structure of 4‐(methylthio)‐4‐nitro‐1‐(pyrrolidin‐1‐yl)buta‐1,3‐diene (2b)The C‐atoms of the butadiene chain have been numbered as shown in 1 and 2. These numbers have been retained throughout the discussion for the sake of clarity and consistency.
indicates the presence of a CH…︁S hydrogen bond. This might also explain the observed downfield shift of this proton in solution.
Synthesis and Odor of Chiral Partial Structures of Khusimone. Part 3. Short communication
Authors: Spreitzer Helmut , Pichler Andrea , Holzer Wolfgang , Schlager Claudia 
Published: December 2004

AbstractKhusimone (1), one of the main odor‐donating compounds of vetiver oil, is subject of the following study on structure/odor relationship. The omittance of the methano bridge of the tricyclic khusimone should lead to the bicyclic partial structure (−)‐2. Unexpectedly, (−)‐2 could not be obtained since epimerization favored (−)‐16. The stereochemical key step of the synthesis of the hydrazulene nucleus is based on a highly diastereoselective conjugate addition to a chiral oxocyclopent‐1‐ene‐1‐carboxylate.
A Convenient Stereoselective Synthesis of (1R,2S,3R,4S)‐3‐(Neopentyloxy)isoborneol
Authors: Verdaguer Xavier , Marchueta Iolanda , Tormo Jordi , Moyano Albert , Pericàs Miquel A. , Riera Antoni 
Published: December 2004

AbstractA convenient preparation of (1R,2S,3R,4S)‐3‐(neopentyloxy)isoborneol (= (1R,2S,3R,4S)‐3‐(2,2‐dimethyl‐propoxy)‐1,7,7‐trimethylbicyclo[2.2.1]heptan‐2‐ol; 1a), a valuable chiral auxiliary, is described. The synthesis involves six steps starting from the readily available camphorquinone (5) and gives 1a in 48% overall yield. The key step is the chemoselective hydrolysis of the less hindered 1,3‐dioxolane moiety in the camphorquinone di‐acetal 4.
Syntheses of O‐Methylasparvenone‐Derived Serotonin‐Receptor Antagonists
Authors: Bös Michael , Stadler Heinz , Wichmann Jürgen , Jenck François , Martin James R. , Moreau Jean‐Luc , Sleight Andrew J. 
Published: December 2004

AbstractBased on O‐methylasparvenone (1), a N‐free 5HT2C antagonist with moderate affinity (pKi = 6.7), derivatives bearing dimethylamino (7), (dimethylamino)methyl (17, 18, 21, and 22), and aminomethyl substituents (26) in place of the benzylic OH group of 1 as well as pyrrolidine‐ (33) and piperidine‐fused derivatives (29, 43, and 45) were synthesized. In contrast to the lead structure 1, these new ligands were active in vivo in the rat. The tricycles 33 and 45 display high affinities for the 5HT2C receptor (pKi = 8).
Synthesis and Properties of Monodisperse Chiral Dendrimers (up to Fourth Generation) with doubly branched building blocks: An intriguing solvent effect
Authors: Murer Peter , Seebach Dieter 
Published: December 2004

Abstract‘Fully chiral’ dendrimers, containing a stereogenic center at each and every branching point, have been prepared using a chiral core triol with aromatic elongating units (cf. 27) and chiral branch diols (cf. 8, 12, and 24) as building blocks. The biggest dendrimer prepared is of the 4th generation (33: 46 building blocks, 93 stereogenic centers, 1028 possible stereoisomers), and has been obtained by a convergent growth approach in 32 steps starting from the biopolymer poly[(R)‐3‐hydroxybutanoic acid] (P(3‐HB)). All compounds were shown to be monodisperse by MALDI‐TOF mass spectrometry. Spin‐lattice relaxation‐time (T1) measurements and size‐exclusion chromatography show typical features of structurally related achiral dendrimers. The influence of the chiral building blocks on the shape of the whole dendrimer has been investigated by chiroptical measurements: the specific rotation can be considered as average of all chiroptical properties of its constituent chiral units, independent of the solvent, the concentration, and the temperature. On the other hand, regularity in the circular dichroism (CD) spectra is completely lost with variation of the solvent (cf. Fig. 13).
A Novel Hydrocarbon, 8,10‐Dimethylidenetricyclo[7.1.1.02,7]undeca‐2,4,6‐triene: Synthesis of benzopinane skeleton via di‐π‐methane rearrangement of benzonorbornadiene system
Authors: Altundaş Aliye , Akbulut Nihat , Balci Metin 
Published: December 2004

AbstractThe [4 + 2] cycloadduct 17 of 2,3‐dimethylidene‐1,2,3,4‐tetrahydro‐1,4‐methanonaphthalene and 4‐phenyl‐4H‐1,2,4‐triazole‐3,5‐dione (PTAD) was subjected to a triplet‐sensitized di‐π‐methane rearrangement. Hydrolysis of the resulting urazol 18 gave the hydrocarbon 7. Hydrolysis of 18 at lower base concentrations led to isomeric stable semicarbazides 24 and 25, which were submitted NiO2 or MnO2 oxidation, to give the target compound 7, and oxidation products 26 and 27.
NMR Verification of Helical Conformations of Phycocyanobilin in Organic Solvents
Authors: Knipp Bernd , Müller Martin , Metzler‐Nolte Nils , Balaban Teodor S. , Braslavsky Silvia E. , Schaffner Kurt 
Published: December 2004

AbstractSelective NMR decoupling and nuclearOverhausereffect (NOE) experiments with phycocyanobilin (PCB) show proton‐proton interactions between the terminal rings A and D,viz. the chiral C(2) methine center and the ethyl substituent at C(18), as a result of the helical conformation of this open‐chain tetrapyrrole in solution. Quantitative NOE measurements and a combination of force‐field and semiempirical calculations (FSC) afford inter‐proton distances across the helical gap of 4.2–4.6 (NOE) and 3.2–4.2 A° (FSC). The NOE and FSC, in conjuction with a qualitative evaluation of the steric interactions in the two optimized helices, suggest furthermore that, in solution, the helixMis somewhat more stable thanP. The coexistence of at least two diastereoisomers is corroborated also by the circular dichroism (CD) spectra of PCB in MeOH/EtOH which point to a temperature‐dependent equilibrium in solution, and by a considerable increase of this CD upon changing the solvent from the achiral alcohols to ethyl (−)‐(S)‐lactate which reflects a selective solvent‐induced CD differentiating between diastereoisomers.
Origin of the Stereoselectivity in (Ethoxycarbonyl)‐, Cyano‐, and Phenyl‐Substituted (Arylsulfinyl)methyl Radicals
Authors: Renaud Philippe , Bourquard Thierry , Carrupt Pierre‐Alain , Gerster Michéle 
Published: December 2004

AbstractAn explanation for the very high diastereoselectivity observed for the reactions of carbonyl‐substituted (arylsulfinyl)methyl radicals is presented, based on experimental results and semiempirical calculations. The influence of dipole‐dipole interactions, allylic 1,3‐strain (A1,3 strain), allylic 1,2‐strain (A1,2 strain), and coulombic interactions is discussed based on stereoselectivities observed with (alkoxycarbonyl)‐, cyano‐, and aryl‐substituted (arylsulfinyl)methyl radicals. In the second part, the effect of solvents and Lewis acids on the stereoselectivity of reactions of (arylsulfinyl)‐ and (alkylsulfinyl)benzyl radicals has been examined.
8‐Fluoro‐6‐(methoxymethoxy)quinoline: Synthesis and regioselective functionalization via reaction with organolithium compounds
Authors: Stadlwieser Josef , Barbier Pierre , Taylor Sven 
Published: December 2004

Abstract8‐Fluoro‐6‐(methoxymethoxy)quinoline (1) was synthesized, and the reactivity of 1 against organolithium compounds was studied under different reaction conditions. With BuLi, directed ortho‐metalation (DoM) was accompanied by 1,2‐addition to the CN bond. 1,2‐Addition was exclusively observed with t‐BuLi. Selective ortho‐metalation was achieved with MeLi (Table). Based on these findings, a short and high‐yielding synthesis of the highly functionalized quinolines 12a–c was developed.
8‐Azaadenosine and Its 2′‐Deoxyribonucleoside: Synthesis and oligonucleotide base‐pair stability
Authors: Seela Frank , Münster Ingo , Lüchner Uwe , Rosemeyer Helmut 
Published: December 2004

AbstractThe synthesis of 8‐azaadenosine (1a; z8A) has been performed by SnCl4‐catalyzed glycosylation of 8‐azaadenine (4) with 1,2,3,5‐tetra‐O‐acetyl‐β‐D‐ribofuranose (5), followed by the separation of the regioisomers 6 and 7 and subsequent deacetylation. The ribonucleoside 1a as well as its 2′‐deoxy derivative 1b (z8Ad) were converted into oligonucleotide building blocks–the phosphonate 2 as well as the phosphoramidites 3 and 19. They were used to prepare the oligoribonucleotide (z8A‐U)6 and oligodeoxyribonucleotides. The Tm values and the thermodynamic data of duplex formation of the modified duplexes showed no significant changes compared to those containing Ad or A residues. This indicates that the stereoelectronic effect of the 8‐azaadenine base which was found for the monomeric nucleoside has only a minor influence on the duplex stability.
Hydrogen Isotope Effect on the Isomerization of Peroxynitrous Acid
Authors: Padmaja Sarojini , Kissner Reinhard , Bounds Patricia L. , Koppenol Willem H. 
Published: December 2004

AbstractThe kinetics of isomerization of deuterium and hydrogen oxoperoxonitrate, ONOOD and ONOOH, respectively, to trioxonitrate(1−), NO, and a deuteron or proton have been studied. Analysis of the pH‐rate profiles result in a normal equilibrium isotope effect (KH/KD) of 3.3. The kinetic deuterium isotope effect for the isomerization reaction is 1.6 ± 0.2 between 5 and 55°. The activation enthalpies of isomerization of ONOOD and ONOOH are identical within the error of the measurement, 86.2 ± 0.5 and 86.5 ± 0.5 kJmol−1, respectively. A secondary kinetic isotope effect of 1.6 is compatible with a mechanism of isomerization where the terminal peroxide O‐atom shifts to the N‐atom.
Isolation of Carotenoids with 3,5,6‐Trihydroxy‐5,6‐dihydro‐β‐end Groups from Red Paprika (Capsicum annuum)
Authors: Deli József , Molnár Péter , Matus Zoltán , Tóth Gyula , Steck Andrea , Pfander Hanspeter 
Published: December 2004

Abstract6‐Epikarpoxanthin ((all‐E,3S,5R,6S,3′R)‐5,‐6‐dihydro‐β,β‐carotene‐3,5,6,3′‐tetrol, 5), 5,6‐diepikarpoxanthin ((all‐E,3S,5S,6S,3′R)‐5,6‐β,β‐carotene‐3,5,6,3′‐tetrol, 13), 5,6‐diepilatoxanthin ((all‐E,3S,5S,6S,3′S5′R,6′S)‐5,6′‐epoxy‐5,6,5′,6′‐tetrahydro‐β,β‐carotene‐3,5,6,3′‐tetrol, 14), and 5,6‐diepicapsokarpoxanthin ((all‐E,3S,5S,6S,3′S,5′R)‐5,6‐dihydro‐3,5,6,3′‐tetrahydroxy‐β,κ‐caroten‐6′‐one, 15) were isolated from red spice paprika (Capsicum annuum var. longum) and characterized by their UV/VIS, CD, 1H‐ and 13C‐NMR, and mass spectra. Our investigations demonstrate that the configuration of the 3,5,6‐trihydroxy‐5,6‐dihydro‐β‐end group may differ depending on the biological source.
Makrocyclische [4n + 2]‐Hückel‐Aromaten bis n = 9 und [4n]‐Antiaromaten bis n = 10: Homologe Reihen vom Tetraepoxy[24]‐annulen(2.0.2.0) zum Tetraepoxy[40]annulen(12.0.12.0) und vom ‘Tetraoxa‐[22]porphyrin(2.0.2.0)’‐zum ‘Tetraepoxa[38]porphyrin(12.0.12.0)’‐Dikation
Authors: Märkl Gottfried , Knott Th. , Kreitmeier Peter , Burgemeister Thomas , Kastner F. 
Published: December 2004

Macrocyclic [4n + 2]‐Hückel Aromatic Systems up to n = 9 and [4n] Antiaromatic Systems up to n = 10: Homologous Sequences from Tetraepoxy[24]annulene(2.0.2.0) to Tetraepoxy[40]annulene(12.0.12.0) and from the ‘Tetraoxa[22]porphyrin(2.0.2.0)‐’ to the ‘Tetraoxa[38]porphyrin(12.0.12.0’‐Dication1)2)Tetraepoxy[32]annulene(8.0.8.0) 3, tetraepoxy[36]annulene(10.0.10.0) 4, and tetraepoxy[40]annulene(12.0.12.0) 5 are synthesized and oxidized to give the ‘tetraoxa[30]‐’, ‘tetraoxa[34]‐’, and ‘tetraoxa[38]porphyrin’ dications 8–10. The annulenes as well as the ‘porphyrins’ are mixtures of at least two different configurational isomers, which can be analyzed by 1H‐NMR techniques. Together with systems described already earlier, a complete homologous sequence from tetraepoxy[24]annulene(2.0.2.0) to tetraepoxy[40]annulene(12.1.12.0) and from ‘tetraoxa[22]porphyrin(2.0.2.0)’ to ‘tetraoxa[38]porphyrin(12.0.12.0)’ dications are available for the first time. The UV/VIS‐absorptionmaxima in the annulene series are shifted to longer wavelengths with an increment of 12 nm per additional CC bonds, and the Δδ values of the 1H‐NMR spectra demonstrate a decreasing paratropic character (Δδ = 5.97 (1), 2.80 (3), and 4.23 ppm (4). The averaged λmax values of the Soret bands of the ‘tetraoxaporphyrin’ dications show a linear bathochromic shift with an increment Δδ of 58 nm per two additional double bonds, the absorptions of the most intensive Q‐bands also increase linearly with an increment of ca. 160 nm. The Δδ values of the 1H‐NMR spectra of the ‘tetraoxaporphyrin’ dications are increasing with the ring size (Δδ = 24.04 (7a) to 25.17 (9a) ppm), respectively, decreasing (Δδ = 21.55 (6) to 21.50 (9b) ppm) with a small maximum of 22.60 ppm for 7b, depending on the configuration of the isomers. The results confirm the antiaromatic character of the annulenes with up to 40π electrons and the aromatic character of the ‘tetraoxaporphyrin’ dications with up to 38π electrons.