Strong Closed-Shell Interactions in Inorganic Chemistry.

8.4.5. Nitromercuration Reactions 3878 9. Hydroamination of Alkenes and Alkynes under Microwave Irradiation 3878 * To whom correspondence should be addressed. Phone: +49 241 8

Hydroamination: direct addition of amines to alkenes and alkynes.

2.3. [4 + 4] Cycloadditions 1058 2.4. Photocycloadditions of Aromatic Compounds 1058 2.4.1. Benzene Derivatives 1058 2.4.2. Condensed Aromatic Compounds 1060 3. Photochemical Rearrangements 1061 4. Cyclizations 1064 4.1. Pericyclizations 1064 4.2. Norrish−Yang Reaction 1066 5. Photochemical Extrusion of Small Molecules 1067 6. Photochemical Electron Transfer 1068 6.1. Photochemical Electron-Transfer Reactions with a Catalytic Sensitizer 1068

Photochemical Reactions as Key Steps in Organic Synthesis

Reversible Photocontrol of Biological Systems by the Incorporation of Molecular Photoswitches

Antibiotics, disinfectants and bacteria resistant to them have been detected in environmental compartments such as waste water, surface water, ground water, sediments and soils. Antibiotics are released into the environment after their use in medicine, veterinary medicine and their employment as growth promoters in animal husbandry, fish farming and other fields. There is increasing concern about the growing resistance of pathogenic bacteria in the environment, and their ecotoxic effects. Increasingly, antibiotic resistance is seen as an ecological problem. This includes both the ecology of resistance genes and that of the resistant bacteria themselves. Little is known about the effects of subinhibitory concentrations of antibiotics and disinfectants on environmental bacteria, especially with respect to resistance. According to the present state of our knowledge, the impact on the frequency of resistance transfer by antibacterials present in the environment is questionable. The input of resistant bacteria into the environment seems to be an important source of resistance in the environment. The possible impact of resistant bacteria on the environment is not yet known. Further research into these issues is warranted.

Resistance in the Environment

New light-Induced Iminyl Radical Cyclization Reactions of Acyloximes to Isoquinolines

I(py)2BF4, a New Reagent in Organic Synthesis: General Method for the 1,2‐Iodofunctionalization of Olefins

Reaction of aromatic compounds with bis(pyridine)iodonium(I) tetrafluoroborate (IPy2BF4) in the presence of HBF4 or CF3SO3H in CH2Cl2 at room temperature furnishes monoiodo derivatives with excellent regioselectivity and yields. Use of either acid gives comparable results with activated aromatics, whereas CF3SO3H is much more effective in the iodination of deactivated aromatics. © 1993 American Chemical Society.

Acid-mediated reaction of bis(pyridine)iodonium(I) tetrafluoroborate with aromatic compounds. A selective and general iodination method

Alkynes react with bis(pyridine)iodonium(I) tetrafluoroborate(1) and nucleophiles (CH 3 COOH, HCOOH, Cl − , pyridine, Br − , I − ) to give 1,2-iodofunctionalized alkenes. The regiochemistry of the processes is in accordance with the polar effects of the triple bond substituents. With regard to stereochemistry, terminal alkynes yield anti addition products, but internal ones produce anti addition with weaker nucleophiles (CH 3 COOH, HCOOH, Cl − , pyridine), syn with stronger nucleophiles (I − ), and a mixture of anti and syn with borderline nucleophiles (Br − ) or when the internal alkyne bears a bulky group. An ionic mechanism through a vinyleneiodonium ion is proposed to explain the obtained results

Pedro J. Campos

Papers

New light-Induced Iminyl Radical Cyclization Reactions of Acyloximes to Isoquinolines

I(py)2BF4, a New Reagent in Organic Synthesis: General Method for the 1,2‐Iodofunctionalization of Olefins

Acid-mediated reaction of bis(pyridine)iodonium(I) tetrafluoroborate with aromatic compounds. A selective and general iodination method

Electrophilic additions of positive iodine to alkynes through an iodonium mechanism

Iodine-Induced Stereoselective Carbocyclizations: A New Method for the Synthesis of Cyclohexane and Cyclohexene Derivatives