Transition-metal-catalyzed addition of heteroatom-hydrogen bonds to alkynes.

The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C–C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of...

Advances in Synthetic Applications of Hypervalent Iodine Compounds

Lewis Acids: From Conventional Homogeneous to Green Homogeneous and Heterogeneous Catalysis

Kraitchman has shown that a single isotopic substitution on an atom is sufficient to determine directly the coordinates of that atom with respect to the principal axes of the original molecule. Kraitchman's formulas represent exact solutions of the equations for the equilibrium moments of inertia. However, the effects of the zero‐point vibrations are such that the coordinates obtained by substitution from the ground state moments of inertia I0 are systematically less than r0. These coordinates have here been called r (substitution) or rs, and it is found that rs≃(r0+re)/2, and Is= ∑ imirsi2≃(I0+Ie)/2.In the usual method of solution, the coordinate of one atom is determined from the equation for I0, and therefore the difference I0—Is must be made up by this one coordinate. This introduces a large error in the structures normally determined from ground state constants, and results in variations of 0.01 A in structures determined from different sets of isotopic species. If instead, we obtain the structure on...

A new criterion for the determination of molecular structures from ground state rotational constants

Additions of Organometallic Reagents to C=N Bonds: Reactivity and Selectivity

Röntgen‐Strukturanalyse eines stabilen Dipols

Aus Carbondiselenid (1) und den 2-Phenyl-substituierten Azirinen 2a, b entstehen unter 1,2-Bindungsspaltung die 3-Selenazoline 5. Beim 2,2-Dimethylazirin 2c bewirkt 1 1,3-Ringoffnung zum zwitterionischen Selenazolin 8a, das in Losung ausschlieslich als Isoselenocyanat 8B vorliegt. Reaktionen von 8 sind sowohl aus der Form A wie aus B moglich. Das 2-monosubstituierte Azirin 2d gibt mit 1 das 2.2′-Biselenazol 23 und das 1-Selenomesoxalsaure-diamid 24. Die Konstitution 23 ergibt sich aus einer Rontgenstrukturanalyse.



Cycloaddition Reactions of Heterocumulenes, XXIV. Selenazole Derivatives from Carbon Diselenide and 3-(Dimethylamino)-2H-azirines



3-Selenazolines 5 result from the reaction of carbon diselenide (1) with 2-phenyl-substituted azirines 2a,b via 1,2-cleavage. In the 2,2-dimethylazirine 2c 1 induces 1,3-ring-opening to give the zwitterionic selenazoline 8a which in solution exists exclusively as isoselenocyanate 8B. Reactions of 8 are possible from form A as well as from B. The 2-monosubstituted azirine 2d reacts with 1 to give the 2,2′-biselenazole 23 and the 1-selenomesoxaldiamide 24. The constitution 23 was derived from an X-ray structural analysis.

Cycloadditionsreaktionen von Heterocumulenen, XXIV. Selenazol-Derivate aus Carbondiselenid und 3-(Dimethylamino)-2H-azirinen

γ-Sultenes and 1,3-Oxazolidinethiones by 1,3-Dipolar Cycloaddition of Thioketene S-Oxides to Azomethines†

Cycloadditionsreaktionen von Heterokumulenen, XV. Umsetzung von persubstituierten Isothioharnstoffen mit Isothiocyanaten und mit Kohlenstoffdisulfid

Cycloadditionsreaktionen von Heterokumulenen, XXIII. Stickstoffhaltige Fünfring‐Heterocyclen aus Carbodiimiden oder Keteniminen mit 3‐Dimethylamino‐2 H‐azirinen

Ernst Schaumann

Papers

Röntgen‐Strukturanalyse eines stabilen Dipols

Cycloadditionsreaktionen von Heterocumulenen, XXIV. Selenazol-Derivate aus Carbondiselenid und 3-(Dimethylamino)-2H-azirinen

γ-Sultenes and 1,3-Oxazolidinethiones by 1,3-Dipolar Cycloaddition of Thioketene S-Oxides to Azomethines†

Cycloadditionsreaktionen von Heterokumulenen, XV. Umsetzung von persubstituierten Isothioharnstoffen mit Isothiocyanaten und mit Kohlenstoffdisulfid

Cycloadditionsreaktionen von Heterokumulenen, XXIII. Stickstoffhaltige Fünfring‐Heterocyclen aus Carbodiimiden oder Keteniminen mit 3‐Dimethylamino‐2 H‐azirinen