No abstract

Aus einfach zuganglichen Pyridinderivaten 10 gelingt mittels Natriumbis(trimethylsiyl)amid (11) die Herstellung der Natriumsalze 12a-c. In ihrer Reaktionsweise gegenuber Elektrophilen 13 weichen die Salze 12 von dem bisher beobachteten Verhaiten seitenkettenmetallierter N-Heteroaromaten 1-4 ab, indem sie sich uberwiegend zu N-derivatisierten 4-Alkyliden-1,4-dihydropyridinen 5a-f umsetzen. Auf der Basis von MNDO-und AM 1-Berechnungen an vereinfachten Modellverbindungen 2a -j wird dieser Befund erkllrt.Seit den Untersuchungen von Ziegler und Zeiser" uber die Herstellung lithiierter Picoline 1 besitzen seitenketten-' metallierte N-Heteroaromaten wie 1 -4 zentrale Bedeutung als einfach zugangliche reaktive Zwischenstufen; die aus ihnen herstellbare Produktpalette ist groD4-?Experimentell wurde nach unserer Kenntnis bisher die ausschlieDliche Bevorzugung des C(a)-Zentrums fur den Angriff zahlreicher, elektronisch recht unterschiedlicher Elektrophile 7 nachgewiesen; G1. (1) faBt einige Umsetzungen fur das Beispiel des 4-Picolins unter Bildung von 6 zusammen.Die Natur der Metalle beeinfluDt bei Anwesenheit mehrerer deprotonierbarer Alkylseitenketten (etwa in der 2-oder 4-Position des Pyridinrings) den Ort der Deprotonierung j4).Wir berichten hier einerseits iiber die Ergebnisse semiempirischer quantenmechanischer Berechnungen mittels der M N D 0 " ) -und (sofern moglich")) der AM 1 ")-Methode an den Modellverbindungen 2a-2j, mit deren Hilfe die bisherigen experimentellen Befunde erklart werden konnen. Andererseits folgt aus dieser Studie eine experimentell uberpriifbare Moglichkeit, die relative Nucleophilie der N( 1)-"Remote Controlled" Nucleophilicity of Anions of some QAlkylpyridines: AM 1-and MNDO-Calculations, Experimental TestsThe easily accessible pyridines 10 are transformed into sodium salts 12a -c by reaction with sodium bis(trimethylsilyl)amide (11). With electrophiles 13, the salts 12 usually react to give N-substituted 4-alkylidene-1,4-dihydropyridines 5a -f. This reaction behaviour differs from the normal behaviour of side chain metalated N-heterornatic compounds 1 -4. Explanations are provided by MNDO and AM1 calculations using the model compounds 2a-j.und C(a)-Zentren durch Variation der Substituenten an C(a) zu steuern.

Dithiocarbimates. Sulfonamides, X-Ray. Sulfones By reaction of the sulfonamides C6H5-SO2-NH2 and p-Cl-C6H4-SO2-NH2 with CS2 in the presence of bases the corresponding dithiocarbimates have been obtained in form of their potassium salts and characterized by means of X-ray structural analysis. Both compounds crystallize in the space group P21/a with a = 29.778(3), b - 6.202(1). c = 7.169(1) Å and β = 90.33(2)° for K2[S2C = N-SO2-C6H5] · 2H2O and a = 31.517(3). b = 7.189(1), c -6.196(1) Å and β = 90.10(1)° for the Cl-substituted species, respectively. A relation between both crystal structures becomes obvious when for K2[S2C = N-SO2-C6H4-Cl] · 2H2O the first space group setting is choosen; i.e. P 1 1 21/a. The dithiocarbimates are built up of two planar moieties. One plane contains the S2C = N-SO framework of each anion while a second plane consists of the S-C6H5 group and the S-C6H4-Cl group, respectively. The two planes are oriented nearly perpendicular to each other and give rise to conjugation involving the SO2 groups in the different systems.

By reaction of K2[S2CNSO2C6H5] · 2H2O and K2[S2CNSO2C6H4Cl] · 2H2O, respectively, with Ni(CH3COO)2 · 4H2O the complex anions [Ni(S2C = N-(SO2-C6H5)2]2- and [Ni(S2C = N-SO2-C6H4-Cl)2]2- are formed and have been isolated in form of their (PPh4) salts. (PPh4)2[Ni(S2C = N-SO2-Ph)2] crystallizes monoclinicly. space group P21/a with a = 19.081(4), b = 9.106(1), c = 17.630(4) Å and β = 113.42(6)° with Z = 2. (PPh4)2[Ni(S2C = N-SO2-C6H4-Cl)2] · 2H2O crystallizes triclinicly, and the non-standard setting Cl has been choosen with a = 15.732(3), b = 22.509(4), c = 9.521(1) Å , ɑ = 96.30(6), β = 117.57(9), γ = 88.93(5)° and Z = 2. Within the complex anions nickel has the site-symmetry 1 and is coordinated by four sulfur atoms with Ni-S mean = 2.198 Å. The Ni(S2C = N-SO)2 units are essentially planar in both systems. This planarity gives rise to conjugation effects involving the SO2 group and the π-system of S2C = N - as well as the lone pair on N.