bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular modeling of saccharides, 8. Selective 2‐O‐benzylation of sucrose: A facile entry to its 2‐deoxy‐ and 2‐keto‐derivatives and to sucrosamine
Authors: Lichtenthaler Frieder W. , Immel Stefan , Pokinskyj Peter 
Published: July 2007

AbstractGeneration of the molecular electrostatic potential (MEP) profiles, in color‐coded form, on the solvent‐accessible contact surfaces of the two main conformations that sucrose adopts in vacuo as well as in aprotic solvents (e.g. DMF), clearly shows the secondary glucosyl‐2‐OH to be the most electropositive of the altogether eight hydroxyl groups–conceivably due to the persistence of an intramolecular hydrogen bond of the 2g‐O…︁HO‐1f type. The notion that the 2g‐OH is accordingly the hydroxyl group most readily deprotonated in aprotic solvents, and that the resulting sucrose 2g‐O‐alkoxide is the one best stabilized by intramolecular hydrogen bonding, received ample substantiation by smoothly achieving a highly regioselective (>80%) 2g‐O‐benzylation in DMF with NaH/benzyl bromide. The resulting 2g‐O‐benzyl‐sucrose (2)– minor products being the 1f‐O‐ (3) and 3f‐O‐isomers (4)– was converted, by acetylation and hydrogenolysis into the 2g‐OH‐free sucrose heptaacetate 6, isolable in crystalline form in 42% yield based on sucrose, thus opening up a ready entry to 2g‐O‐modified derivatives: 2‐deoxy‐sucrose (12) via radical deoxygenation of a 2g‐O‐thiocarbamate, 2‐keto‐sucrose perbenzoate 7 via PDC oxidation, or N‐acetyl‐sucrosamine 14 and its manno‐analog 16 through oximation of 7 and subsequent borane reduction.
Asymmetric synthesis of chiral, nonracemic dialkyl α‐hydroxyarylmethyl‐and α‐, β‐ and γ‐hydroxyalkylphosphonates from keto phosphonates
Authors: Meier Chris , Laux Wolfgang H. G. , Bats Jan W. 
Published: July 2007

AbstractThe enantioselective synthesis of α‐hydroxyarylmethylphosphonates 2a‐p by the oxazaborolidine‐catalyzed reduction of α‐keto phosphonates 1a‐p using different boranes 4a–c was studied in detail. Moderate to good enantioselectivities are found (up to 80% ee) by using the borane‐dimethyl sulfide complex 4a as reducing reagent and the 2‐n‐butyl derivative of the (S)‐5,5‐diphenyl‐3,4‐trimethylene‐1,3,2‐oxazaborolidine catalyst 3b. In contrast, excellent enantiomeric excesses (up to 99% ee) as well as high chemical yields are obtained when catecholborane 4c in combination with low temperature is introduced. Substituent effects on the starting material 1 are discussed with the help of structural information obtained by X‐ray analyses of the benzoylphosphonates 11fγ, 1jγ, and 1nγ. A slight decrease in enantioselectivity was found within the series of α‐, β‐, and γ‐hydroxyalkylphosphonates 6, 8, and 10, respectively. Nevertheless, even these compounds are reduced with enantioselectivities ranging from 68% (10) to 95% (6) by using catecholborane 4c and catalyst 3b. On the other hand, we synthesized the allylic α‐hydroxyphosphonate 12 in 75% chemical yield and with 56% enantiomeric excess by means of this methodology. The reaction has subsequently been applied to the synthesis of α‐hydroxyalkylphosphonates 14a–c, which were obtained with ee values up to 90%. Compounds 14 are useful precursors for the synthesis of the P‐amino acids 15.
α‐Thiotetronic Acids, II. Reactions of γ‐Alkylidene‐α‐Thiotetronic Acids
Authors: Stachel Hans‐Dietrich , Zeitler Klaus 
Published: July 2007

AbstractThe α‐thiotetronic acid 1 reacts with amines predominantly with ring opening to give polyfunctionalized ketones (2) which readily cyclize to α‐tetramic acid amides (4a, b). The reaction of α‐thiotetronate 6 with nucleophiles is more complex, leading to either an open‐chain derivative (8) or formation of an α‐thiotetronic acid amide (3b) or an α‐tetramate (4f). Treatment of 6 with sodium sulfide in air furnishes the salt of the 1,2‐dithiole 10. The dibrominated α‐thiotetronate 13a reacts with N and S nucleophiles predominantly by substitution, leading finally to the bisthiolactones 14 or the thieno‐1,2‐dithioles 17.
Studies on ketoses, 10. Acylation and carbamoylation of D‐fructose: Acyclic, furanoid and pyranoid derivatives and their conformational features
Authors: Lichtenthaler Frieder W. , Klotz Jürgen , Flath Franz‐Josef 
Published: July 2007

AbstractAcylations of D‐fructose are complicated at several levels. The product distribution is determined not only by the rate of equilibration of the crystalline β‐p‐form in pyridine to the α‐p, β‐f, and α‐f‐tautomers, but also by the distribution of these forms at a given temperature, as well as their individual hydroxyl group. A detailed study of these parameters resulted in the elaboration of new or improved procedures for the practical, straightforward preparation of either acyclic, furanoid, or pyranoid benzoyl and pivaloyl derivatives, as well as cyclocarbamates with 1,2‐spiro‐annelated and 2,3‐bridging oxazolidinone rings. Accordingly, a variety of simple, tautomerically fixed fructose derivatives, most notably those of the α‐p, α‐f and β‐f forms, are now easily accessible for exploitation as versatile enantiopure building blocks. The structures, anomeric configurations and conformations of the various products obtained were determined on the basis of their 1H and 13C NMR data. The furanoid cases required the support of two X‐ray structures: the pentabenzoyl‐α‐D‐fructofuranose (9) which has an E2 conformation, and the 2,3‐cyclocarbamate 25, in which the β‐furanose ring adopts a 5E geometry.
Trapping reactions of sulfenes generated from sulfonic acid derivatives and bases, 1. Cyclopentadiene, methylcyclopentadiene and 1,2,3,4‐tetraphenylcyclopentadiene used as sulfene scavengers. [4 + 2] cycloaddition reactions and sulfonylations
Authors: Opitz Günter , Deißler Michael , Ehlis Thomas , Rieth Karlheinz , Irngartinger Hermann , Ziegler Manfred L. , Nuber Bernhard 
Published: July 2007

AbstractThe bulky sulfenes generated in situ from (+)‐10‐camphor‐, 10‐camphane‐, and 2‐methyl‐2‐phenylpropanesulfonyl chloride (1a–c) and Et3N can be trapped by cyclopentadiene to give the [4 + 2] cycloadducts 6a–c. The mixture of endo‐6a and exo‐6a (no other diastereomers) is formed by complete asymmetric induction. In MeCN solution additionally the 1,3‐di‐ and 1,2,4‐trisulfonylated cyclopentadienides 4a–c and 5a (X‐ray analysis) + 5c were obtained. On acidification, 4a and 5a were transformed into the pentafulvenoid derivatives 8a, 9a, 10a. The reaction of (+)‐10‐camphorsulfonyl chloride (1a)/Et3N with 1,2,3,4‐tetraphenylcyclopentadiene afforded the sulfonylated product 11a, with 2‐methylcyclopentadiene 50% endo‐12a (X‐ray analysis) and 10% exo‐12a. From cyclopentadiene and the more electrophilic cyanosulfene (2e) and mesylsulfene (2f, X = Me), generated in situ from cyanomethanesulfonyl chloride (1e)/Et3N and from mesyl chloride/Et3N, the [4 + 2] cycloadducts 6e and 6g were obtained. Similarly, methanedisulfonyl dichloride (1f, X = Cl)/Et3N afforded stereospecifically by two subsequent [4 + 2] cycloadditions the spirodisulfone 16 (X‐ray analysis).
Cascade reactions with chiral michael acceptors; synthesis of enantiomerically pure tricyclo[3.2.1.02,7]‐ and bicyclo[3.2.1]octanes
Authors: Braun Norbert A. , Klein Iris , Spitzner Dietrich , Vogler Bernhard , Braun Siegmar , Borrmann Horst , Simon Arndt 
Published: July 2007

AbstractStarting from the easily accesible chiral aldehyde 2, we obtained enantiomerically pure (Z)‐ and (E)‐α,‐chloro‐α,β‐unsaturated esters 4c in good yields by olefination reactions. (Z)‐and (E)‐4c were allowed to react with the kinetically controlled generated lithium dienolate Li‐7 to give the enantiomerically pure tricyclo[3.2.1.02,7]octanes 8 and 9, respectively. The „push‐pull”︁ substituted cyclopropane moiety of 8 was opened to give solely bicyclo[3.2.1]octane 10.
5′,5′‐di‐O‐nucleosyl‐O′‐benzylphosphotriesters as potential prodrugs of 3′‐azido‐2′,3′‐dideoxythymidine‐5′‐monophosphate
Authors: Meier Chris , Habel Lothar W. , Balzarini Jan , De Clercq Eric 
Published: July 2007

AbstractThe synthesis of 5′,5′‐O‐di‐(3′‐azido‐2′,3′‐dideoxythymidinyl)‐O′‐benzylphosphotriesters 1 as potential prodrugs of nucleoside monophosphates is described. The concept is applied to the antiretroviral nucleoside analog 3′‐azido‐2′,3′‐deoxythymidine (AZT) 4. All derivatives 1 were synthesized by reaction of the tetra‐n‐butylammonium salt of di‐AZT‐phosphate 2b with different benzyl bromides or ‐chlorides 9. Compound 2b was obtained by a combination of phosphoamidite/H‐phosphonate chemistry, subsequent oxidation to 2a, and cation exchange. The partition coefficients of 1 in an 1‐octanol/water mixture show that all compounds exhibit a much higher lipophilicity than the parent nucleoside AZT (4). It was also shown, that 1 decomposes spontaneously under mild aqueous basic conditions (phosphate buffer (pH 7.5) and RPMI culture medium containing heat‐deactivated fetal calf serum) releasing selectively the di‐AZT phosphate anion 2. The half‐lives of 1 could be adjusted within a wide range by changing the ring substituents of the benzyl group. Additionally, the mechanism of hydrolysis varies if the substituent is changed from a donor to an acceptor one. The described phosphotriesters 1 exhibit considerable antiviral activity in HIV‐1‐ and HIV‐2‐infected CEM/O cells, whereas no activity was detected in the HIV‐2‐infected thymidine kinase‐deficient CEM cell line. On the other hand, we could not detect any cytotoxicity of the described phosphotriesters. Consequently, compounds 1 should act as prodrugs or depot forms at least of antiviral nucleoside analogs.
EPR Study of the Radical Ions of Aryl‐Substituted Propellanes
Authors: Crockett Rowena , Gescheidt Georg , Dyker Gerald , Körning Jutta 
Published: July 2007

AbstractThe radical anions and the radical cations of 1–3 in which three π systems are connected in three dimensions by a strained propellane spacer were studied by ESR/ENDOR/TRIPLE spectroscopy. The hyperfine data of acenaphthene (4) are compared with those of the fused π systems 5–10. In the relatively persistent radical anions of 1–3, the spin is mainly confined to the two naphthalene moieties. Whereas the radical cation of 2 resembles a naphthalene trimer, the radical cations of intact 1 and 3 cannot be detected. The ESR spectra recorded upon one‐electron oxidation of 1 and 3 are assigned to the radical cations of 9 and 10, respectively, formed by the loss of one naphthalene moiety from the parent molecules.
Zwitterions as Intermediates in 1,3‐Dipolar Cycloadditions of Electrophilic Azides to 2‐Alkylidenetetrahydroimidazoles and 2‐Alkylidenedihydrobenzimidazoles
Authors: Quast Helmut , Ach Manfred , Ivanova Svetlana , Peters Eva‐Maria , Peters Karl , von Schnering Hans Georg 
Published: July 2007

AbstractCyclic ketene N,N‐acetals derived from imidazolidine (4a, c) and 2,3‐dihydrobenzimidazole (6a–c) add methanesulphonyl azide (2a) or picryl azide (2f) to afford the zwitterions 5 and 7, respectively. The structure of 7d is elucidated by X‐ray crystallography. Reversibility of formation and thermal stability of the N‐sulphonyl zwitterions depend on the substitution pattern at the carbon atom to which the triazenide moiety is attached: In the case of a pair of geminal methyl groups (5a, 7a) formation is irreversible and decomposition by cyclisation and subsequent reactions occurs above −20°C, while in presence of a single alkyl group (7c, d) these processes require heating to 80°C and are accompanied by partial reversion to 2a and ketene N,N‐acetals (6b, c). Cyclisation of the zwitterions yields intermediate spirocyclic [3 + 2] cycloadducts, which may undergo [3 + 2] cycloreversion into N‐sulphonylimine 13 and diazo compound 14 or extrude molecular nitrogen to furnish ring‐expanded 2‐(sulphonylimino)piperazine derivatives (9, 11).
A Practical Synthesis of Enantiopure (R)‐4‐Hydroxy‐2‐cyclohexen‐1‐one
Authors: Gebauer Olaf , Brückner Reinhard 
Published: July 2007

AbstractThe title compound R‐4a was prepared from (–)‐quinic acid (1) in 6 steps in 18% overall yield (Scheme 3) and with 100% enantiomeric purity (Figure 1). The initiating step is the regio‐ and stereoselective acetalization of the trans‐oriented vicinal OH groups of 1 (+ 5 → 8). Alcohol R‐4a can be protected as the 2‐ethoxyethyl ether R‐4e (78%).
Photochemical Behavior of Doubly Bridged Dewar Benzenes – Synthesis of Prismanes
Authors: Gleiter Rolf , Ohlbach Frank , Haberhauer Gebhard , Irngartinger Hermann , Oeser Thomas 
Published: July 2007

AbstractIn this paper we report on the photochemistry of Dewar benzenes bridged at the 1,4‐ and 5,6‐positions and substituted at the 2,3‐positions. It was found that simple alkyl substitution leads to prismanes only to a minor extent. Introduction of phenyl groups into the 2‐ or 2,3‐positions gives the corresponding doubly bridged prismanes in yields up to 80% Pentamethylene‐bridged bis‐Dewar benzenes 19 rearrange upon irradiation to 22. Irradiation of the doubly bridged Dewar benzene derivatives with one ester group at the 5‐position does not yield isolable products. However, introduction of one tert‐butylsulfonyl group such as 30–33 gives almost quantitative yields of isolable prismanes if pentamethylene or hexamethylene bridges are used. The nonbridged species, 2‐tert‐butylsulfonyl‐1,4,5,6‐tetramethylbicyclo[2.2.0]hexa‐2,5‐diene (44), aromatizes upon irradiation into 1‐(tert‐butylsulfonyl)‐2,3,4,5‐tetramethylbenzene (45). In contrast to the pentamethylene‐bridged monosulfone 47, the corresponding disulfone 38 undergoes no photochemical reaction. This could be explained by the X‐ray structure, which reveals a strong interaction between one of the tert‐butyl groups and the pentamethylene chain bridging the double bond in 38.
Conformations and Rotational Barriers of (Z)‐1,2‐α‐Naphthostilbene Crown Ethers and Their Alkali Metal Complexes
Authors: Merz Andreas , Gromann Lutz , Karl Andreas , Burgemeister T. , Kastner F. 
Published: July 2007

AbstractThe synthesis of 2,3‐didehydro[15]crown‐5 and −[18]crown‐6 derivatives 4a, b with vicinal α‐naphthyl groups at the double bonds starting from α‐naphthoin (3) is described. The barriers to rotation of the naphthyl groups were probed by MM2 and by dynamic 1H‐NMR spectroscopy. An achiral syn and a chiral anti conformation were experimentally observed at −90°C for the free ligands and at −40°C for the complexes. The experimental ΔG≠ and the calculated ΔH≠ values are in fair agreement. The barriers are substantially higher in the alkali metal complexes than in the free ligands. In the presence of racemic and potassium S‐(+)‐mandelate non‐equilibrating ion pairs with 4b were observed by low‐temperature 1H‐NMR spectroscopy for the anti conformation.
A Conformational Study of [3.3](2,6)Pyridinophane by the Dynamic NMR Method and X‐ray Structural Analysis
Authors: Sako Katsuya , Tatemitsu Hitoshi , Onaka Satoru , Takemura Hiroyuki , Osada Satoshi , Wen Gang , Shinmyozu Teruo , Rudziński Jerzy M. 
Published: July 2007

AbstractA variable‐temperature 1H‐NMR study and X‐ray structural analysis show that the most stable conformational isomer of [3.3](2,6)pyridinophane 2 is the syn(boat‐boat) conformer, and the relative stability order of the three stable conformers is syn(boat‐boat) > syn(chair‐boat) > syn(chair‐chair). This is in sharp contrast to the relative stability order of the parent [3.3]metacyclophane 1: syn(chair‐chair) > syn(chair‐boat) > syn(boat‐boat). The high stability of the syn(boat‐boat) conformer 2c is primarily attributed to weak attractive interactions via intramolecular hydrogen bonds between nitrogen lone pairs (N‐1, N‐2) and the axial hydrogen atoms (2A‐H, 11A‐H) on the central carbon atoms of the bridges, as suggested by their short transannular distances (2.50 Å).
Synthesis of 4′,7‐Dihydroxy‐6‐methoxyisoflavone 7‐O‐β‐d‐Glucopyranoside (Glycitin)
Authors: Nógŕdi Mihály , Szöllosy Áron 
Published: July 2007

AbstractThe aglycone glycitein (1) of the title glucoside glycitin (2) was prepared by oxidative rearrangement of the fully protected chalcone 4 by Tl(NO3)3 in MeOH into 5 followed by deprotection and ring closure. Its glucosylation with α‐acetobromoglucose and subsequent saponification gave 2 as the main product.
2‐Chloro‐4,5‐dihydroimidazole, 8. Syntheses of Novel Fused Heterocyclic Systems by Reactions of 1,2‐Dihydro‐2‐(4,5‐dihydroimidazol‐2‐yl)phthalazin‐1‐ol with Active Methylene Compounds
Authors: Saczewski Franciszek , Gdaniec Maria 
Published: July 2007

AbstractThree‐component reactions of 1 with pyridazine or phthalazine afforded the 1,2‐dihydro derivatives 2a and 2b, respectively. A similar reaction of 1 with phthalazine performed in aqueous NaOH led to the formation of pseudobase 3. The latter compound proved to be an excellent substrate for the preparation of a series of novel 1,2‐dihydrophthalazine derivatives 4a–c, 5 as well as 6a–b by reactions with a variety of active methylene compounds.
A New Assay For Sialyltransferases Using Fluorescein‐Labelled Acceptors
Authors: Limberg Gerrit , Slim George C. , Furneaux Richard H. , Compston Catharine A. , Stangier Peter , Palcic Monica M. 
Published: July 2007

AbstractA novel HPLC assay system for sialyltransferase activity based on the use of fluorescein‐labelled acceptor oligosaccharides is described. The fluorescein‐labelled disaccharides βGal‐(1→4)‐βGlc‐OR (4), βGal‐(1→4)‐βGlcNAc‐OR (17), and βGal‐(1→3)‐βGlcNAc‐OR (22) where OR consists of a six carbon spacer with fluorescein attached, were synthesised. Synthetic standard products were produced chemo‐enzymatically on a preparative scale to yield fluorescein‐labelled trisaccharides. The use of reverse phase HPLC with an ionpairing agent allowed the separation of starting materials from products and separation of the two isomeric trisaccharides αNeu5Ac‐(2→3/6)‐βGal‐(1→4)‐βGlcNAc‐OR (24 and 25), so that the assay could be used to measure the different silalyltransferase activities in a mixture. The assay was successfully applied to the detection of sialyltransferase activity of commercially available enzymes and a crude preparation of bovine colostrum. The predominant sialyltransferase activity in bovine colostrum adds sialic acid α(2–6) to 17.
Synthesis of Protected Enantiopure Erythrulose Derivatives
Authors: Alberto Marco J. , Carda Miguel , González Florenci , Rodríguez Santiago , Murga Juan 
Published: July 2007

AbstractD‐ and l‐Erythrulose derivatives 2–6 bearing protective O‐silyl and O‐benzyl groups in various positions were synthesized in enantiopure form from l‐ascorbic acid, D‐isoascorbic acid, and D‐glucose.
Pheromone Synthesis, CLXXVI. Synthesis of the Four Stereoisomers of 3,13‐Dimethylheptadecane, the Major Sex Pheromone Component of the Western False Hemlock Looper
Authors: Takikawa Hirosato , Shirai Yasuo , Kobayashi Makoto , Mori Kenji 
Published: July 2007

AbstractAll of the four stereoisomers of 3,13‐dimethylheptadecane (1), the female‐produced sex pheromone of the western false hemlock looper (Nepytia freemani), were synthesized by starting from the enatiomers of citronellol (2a) and 2‐methyl‐1‐butanol (4a).
Photochemistry of [2.2]Paracyclophan‐enes — a Matrix‐Isolation Study
Authors: Marquardt Ralph , Sander Wolfram , Laue Thomas , Hopf Henning 
Published: July 2007

AbstractThe UV photolysis of [2.2]paracyclophan‐ene (3) and benzo‐[2.2]paracyclophan‐ene (4), matrix‐isolated in argon at 10 K, results in the cleavage of the ethano bridge and formation of compounds5and8, respectively. The IR and UV/Vis spectra are compared withp‐xylylene and the benzyl radical as models for a quinoid or diradicaloid structure. The absence of an ESR signal reveals a singlet ground state for these compounds. Remarkable is a sharp absorption in the red part of the visible spectrum which is not observed in the case ofp‐xylylene or the benzyl radical. The electronic structure can be described as quinoid with a substantial amount of diradicaloid character.
Nitroalkanes as Alkyl Anion Synthons — A New Approach to the Synthesis of 2‐Substituted N‐Ethyl Succinimides and 2‐Substituted Succinate Diesters via Nitroalkanes
Authors: Ballini Roberto , Bosica Giovanna 
Published: July 2007

Abstract2‐Substituted N‐ethyl succinimide and 2‐substituted succinate diesters were obtained by two key steps: (i) Michael addition of a nitroalkane to the appropriate enedione derivative under basic conditions (DBU), with the concomitant elimination of nitrous acid, and (ii) selective reduction of the obtained enone with nickel boride, in methanol/THF. In this context the nirtoalkane acts as an alkyl anion synthon. By this method trimethyl tricarboxylates were also synthesized.
Monolayer and Bilayer Stability of Ammonium Amphiphiles Carrying an Azobenzene Unit – Effects of Substituents at the Azobenzene Unit
Authors: Everaars Marcel D. , Marcelis Antonius T. M. , Sudhölter Ernst J. R. 
Published: July 2007

AbstractNovel double‐chained ammonium amphiphiles carrying one azobenzene moiety (I) have been synthesized. The bilayer‐stabilizing effect of different azobenzenes (ABs) has been investigated by measuring the “gel‐to‐liquid crystalline” phase transition temperatures of the formed bilayers in water using differential scanning calorimetry. It is found that the stabilizing effect of the azobenzenes strongly depends on the substituents at the aromatic ring. The stabilizing effect increases in the sequence F < H < NO2 < CN < OCH3 < N=N–Ph, which cannot be correlated with the electron‐withdrawing or ‐donating properties of the substituents. It is concluded that dipole‐dipole interactions between the ABs are of minor importance for the overall stabilization of the bilayer. Instead, other factors determine the strength of the van der Waals interactions between the ABs. In the bilayers the ABs form H‐aggregates as is observed by the blue shift of the UV absorption maximum. This blue shift is not affected by the “gel‐to‐liquid crystalline” phase transition. Bilayers of I–N=N–Ph do not exchange monomers with vesicles of didodecyldimethylammonium bromide, whereas all other investigated bilayers do. Compound I–N=N–Ph forms monolayers at the water‐air interface, which are much more stable than the monolayers of the other investigated compounds.
Quantification of the Electrophilicities of Diazonium Ions
Authors: Mayr Herbert , Hartnagel Manfred , Grimm Klaus 
Published: July 2007

AbstractThe kinetics of the reactions of arenediazonium ions with arenes, alkenes, allylsilanes, allylstannanes, and silyl ketene acetals have been studied in acetonitrile solution. The reactions follow second‐order kinetics, and in several cases rate‐determining attack of the diazonium ion has been proven by kinetic isotope effect studies (1a + 2b), by the independence of the allylsilane reactivities of the rate of desilylation (1a + 10a, d) and by the independence of the rate constants of the diazonium counterion. A decrease of the rate constant with increasing solvent donor ability (correlation with Gutmann's donor number) was found. The reactions of diazonium ions with π‐nucleophiles roughly follow the correlation lgk (20°C) = s (E + N), previously derived for the reactions of carbocations with nucleophiles. With the E parameters derived for diazonium ions, rate constants for azo couplings with aromatic and nonaromatic π‐nucleophiles can be predicted with an accuracy of ≈102. On the basis of E, the electrophilic reactivities of diazonium ions can be compared with those of carbocations (Figure 9), and the combination with the nucleophilicity parameters N (Figure 10) gives a first clue on possible azo coupling reactions. Literature reports are discussed within this scheme.