Chlorination of Phosphane Selenides

Catalytic Metal-free Allylic C-H Amination of Terpenoids

The selective replacement of C-H bonds in complex molecules, especially natural products like terpenoids, is a highly efficient way to introduce new functionality and/or couple fragments. Here, we report the development of a new metal-free allylic amination of alkenes that allows the introduction of a wide range of nitrogen functionality at the allylic position of alkenes with unique regioselectivity and no allylic transposition. This reaction employs catalytic amounts of selenium in the form of phosphine selenides or selenoureas. Simple sulfonamides and sulfamates can be used directly in the reaction without the need to prepare isolated nitrenoid precursors. We demonstrate the utility of this transformation by aminating a large set of terpenoids in high yield and regioselectivity.

Bromination and iodination of diphosphane dichalcogenides

The diphosphane dichalcogenides dppmSe₂, dppeSe₂, dⁱprpmSe₂, dⁱprpeSe₂, dppmS₂ and dppeS₂, [dppm = bis(diphenylphosphano)methane, dppe = bis(diphenylphosphano)ethane, dⁱprpm = bis(diisopropylphosphano)methane, dⁱprpe = bis(diisopropylphosphano)ethane] have been treated with elemental bromine or iodine and the products 1-15 characterized by single crystal X-ray diffraction. DppeSe₂ with bromine or iodine gives the simple (and previously known) adducts dppe(SeBr₂)₂1 or dppe(SeI₂)₂2 respectively; dⁱprpeSe₂ reacts similarly to give dⁱprpe(SeBr₂)₂3 (at 0 °C) or dⁱprpe(SeI₂)₂4. The bromine derivatives display a T-shaped geometry at selenium, whereas the iodine derivatives involve linear Se-I-I groups. With dppmSe₂ and bromine, a product was formed at -50 °C, but could not be isolated; at room temperature the reaction leads to a mixture of products, from which only [dppmBr₂]²⁺ [Se₂Br₁₀]^2-5 (the anion involving a dibromine molecule coordinating to a Se centre) could be isolated. Reaction of dppeSe₂ with excess bromine at room temperature leads to [dppeBr₂]²⁺·½[SeBr₆]^2-·[SeBr₂·Br₂·Br₃]^-6. The reaction of dppmSe₂ with iodine gives the 1 : 2 adduct [dppmSe₂I]⁺ [I₃]^-7, the cation of which contains a novel five-membered CP₂Se₂ heterocycle. In a 1 : 1 ratio the same reaction gives another 1 : 2 adduct, [I₂Se(dppm)Se-I-Se(dppm)SeI₂]⁺ [I₃]^-8. DⁱprpmSe₂ with iodine gives [dⁱprpmSe₂I]⁺ [I₃]^-9, analogous to 7, and with bromine at 0 °C the corresponding product [dⁱprpmSe₂Br]⁺ [Br₃]^-10. At room temperature, dⁱprpeSe₂ reacts with bromine to give a mixture of [dⁱprpe(SeBr₂)Br]⁺ Br^-11 and [dⁱprpeBr₂]²⁺ [SeBr₄]^2-12, whereas dⁱprpmSe₂ forms [dⁱprpmBr₂]²⁺ [SeBr₄]^2-13, analogous to 12. The disulfides dppmS₂ and dppeS₂ react with bromine to give [dppmSBr]⁺ [Br₃]^-14 and [dppeSBr]⁺ [Br₃]^-15.

Aminkomplexe des Goldes, Teil 9: Gold(I)-halogenid-Komplexe mit primären und azyklischen sekundären Aminen und ihre Oxidation zu Gold(III)-Derivaten

The reaction of (tht)AuX (X=Cl or Br; tht=tetrahydrothiophene) with various primary amines L leads to products of the form [L2Au]+X−. Packing diagrams of the corresponding structures are dominated by N–H···X hydrogen bonds and (in some cases) aurophilic contacts. The cyclohexylamine derivative was already known as its dichloromethane ⅔-solvate; we have isolated the solvent-free compound and its pentane ¼-solvate, which all show different packing patterns. With acyclic secondary amines, the products are more varied; LAuX and [L2Au]+[AuX2]− were also found. These gold(I) products were generally formed in satisfactory quantities. The attempted oxidation to Au(III) derivatives with PhICl2 or Br2 proved impossible for the primary amine derivatives [although isopropylamine-trichloridogold(III) was obtained unexpectedly from the corresponding cyanide] and unsatisfactory for the secondary amine derivatives. Products LAuX3 and [L2AuX2]+[AuX4]− were identified but were formed in disappointing yields. In isolated cases protonated products (LH)+[AuCl4]−, (LH+)3[AuCl4]−(Cl−)2 or [(Et2N)2CH]+[AuBr4]− were formed, presumably by involvement of the dichloromethane solvent and/or adventitious water. Here also the yields were poor, and some products arose as mixtures. Direct reaction of amines with AuCl3 or (tht)AuX3 was also unsuccessful. All products were characterized by X-ray structure analysis.