Tore Hansen

A General Approach for Preparation of Polymer-Supported Chiral Organocatalysts via Acrylic Copolymerization

Polymer-supported chiral organocatalysts, as well as most other forms of immobilized catalysts, are traditionally prepared by a postmodification approach where modified catalyst precursors are anchored onto prefabricated polymer beads. Herein, we report an alternative and more scalable approach where polymer-supported chiral enamine and iminium organocatalysts are prepared in a bottom-up fashion where methacrylic functional monomers are prepared in an entirely nonchromatographic manner and subsequently copolymerized with suitable comonomers to give cross-linked polymer beads. All syntheses have been conducted on multigram scale for all intermediates and finished polymer products, and the catalysts have proven successful in reactions taking place in solvents spanning a wide range of solvent polarity. While polymer-supported proline and prolineamides generally demonstrated excellent results and recycling robustness in asymmetric aldol reactions of ketones and benzaldehydes, the simplest type of Jørgensen/Hayashi diarylprolinol TMS-ether showed excellent selectivity, but rather sluggish reactivity in the Enders-type asymmetric cascade. The polymer-supported version of the first-generation MacMillan imidazolidinone had a pattern of reactivity very similar to that of the monomeric catalyst, but is too unstable to allow recycling.

Synthesis of Acrylic Polymer Beads for Solid-Supported Proline-Derived Organocatalysts

A completely non-chromatographic and highly large-scale adaptable synthesis of acrylic polymer beads containing proline and prolineamides has been developed. Novel monomeric proline (meth)acrylates are prepared from hydroxyproline in only one step. Free-radical copolymerization then gives solid-supported proline organocatalysts directly in as little as two steps overall, without using any prefabricated solid supports, by using either droplet or dispersion polymerization. These affordable acrylic beads have highly favorable and adjustable swelling characteristics and are excellent reusable catalysts for organocatalytic reactions.

Computational Study of Cyclopropanation Reactions with Halodiazoacetates

The mechanism of rhodium(II)-catalyzed cyclopropanation reactions with ethyl bromo-, chloro-, and iododiazoacetate has been studied with density functional theory calculations. The halodiazoacetates were shown to be remarkably kinetically active compared to ethyl diazoacetate, as demonstrated experimentally in a study of reaction rates and supported by the calculated low potential energy barriers for the rate-determining loss of dinitrogen. In the rhodium carbenoids formed from the halodiazoacetates, pi-interactions between the halogen, the carbenoid carbon, and one rhodium atom were found. These interactions provide an explanation for the relatively high stability of these carbenoids and, consequently, the existence of small but significant potential energy barriers for the cyclopropanation step. The predicted diastereomeric ratios correspond well with the experimental results. In addition to transition states in which the alkene approaches the carbenoid in an end-on manner, as described in computational studies of cyclopropanations with other diazo compounds, side-on trajectory transition states were found to be of importance. The relative energies of the side-on trajectory transition states compared to the end-on trajectory transition states were shown to be affected by both the substrate alkene and the carbenoid substituents, a fact that should be taken into consideration when using models to explain and predict the stereochemical outcome of cyclopropanation reactions.

Budgetary Strategies and Success at Multiple Decision Levels in the Norwegian Urban Setting

The purpose of this article is to test a series of propositions about budgetary decision making, in the form of linear decision models, for the municipal government of Oslo, Norway, and to assess the consequences of such strategic choices for the long-term growth of agency activities. Budgetary decisions for forty-seven agencies at each of the four principal decision-making levels over a nineteen-year period serve as the basis for analysis. Results indicate that while the complexity of strategic choice is not related to long-term agency growth, the acquisitiveness of the agency strategy is an important determinant of growth. Intermediate budgetary reviewers are only partially successful in reducing the relationship between acquisitiveness and growth. Reference to a set of systematic interview materials in these same agencies, relevant to the cognitive assumptions of the models, suggests some reservations about model validity, at least in a minority of cases.

Halodiazophosphonates, a New Class of Diazo Compounds for the Diastereoselective Intermolecular Rh(II) Catalyzed Cyclopropanation

(Halodiazomethyl)phosphonates 2A-C have been generated by a one-pot procedure via a clean, efficient, and rapid deprotonation/electrophilic halogenation sequence from diethyl diazomethylphosphonate 1 (EDP). Subsequent intermolecular Rh(II)-catalyzed cyclopropanation afforded the corresponding halocyclopropylphosphonates 3-10 in moderate to high yields and high diastereomeric ratios. Catalyst loadings down to 0.1 mol % as well as clean and selective product formation were achieved.

Halodiazoacetates as useful tools for selective halo-functionalization

The halodiazoacetates are a group of synthetically useful halogenated diazo compounds that can be used in Rh(II)-catalyzed carbenoid reactions. In the reactions between the halodiazoacetates and electron-rich, sterically unhindered alkenes, halocyclopropanes are formed in good to excellent yields. The halodiazoacetates also react well in C–H and Si–H insertion reactions, broadening the synthetic utility of these reactions. The products of the reactions are synthetically useful α-halocarbonyl compounds. Density functional theory (DFT) calculations have given insight into the mechanism of the cyclopropanation and C–H insertion reactions of the halodiazoacetates, and have also shown that the halodiazoacetates have a particularly high kinetic activity.

tert-Butyl 4-(2-diazo-acet-yl)piperazine-1-carboxyl-ate.

The title crystal structure, C11H18N4O3, is the first diazoacetamide in which the diazoacetyl group is attached to an N atom. The piperazine ring is in a chair form and hence the molecule has an extended conformation. Both ring N atoms are bonded in an essentially planar configuration with the sum of the C—N—C angles being 359.8 (2) and 357.7 (2)°. In the crystal structure, the O atom of the diazoacetyl group accepts two H atoms from C—H donors, thus generating chains of weak hydrogen-bonded R 2 1(7) rings.

Cyclopropanation of Olefins with Nitromethane

A procedure for the use ofnitromethane as an iodonium ylide precursor has been developed. Electron-rich olefins are cyclo-propanated with nitromethane in the presence ofbis(acetoxy)iodobenzene, a base and a Rh(II) catalyst to provide nitrocyclopropanes in moderate to good yields.

The Politics of Local Planning in Norway

The aim of this article is to assess the political conditions for an efficient local planning, giving first an outline of the current planning system in Norway and turning then to the relationship between planning and local politics. The perceptions and attitudes of local concillors in relation to planning are presented on the basis of data from a questionnaire survey, which included about 400 local councillors in 16 Norwegian municipalities. The data suggest that a substantial majority of the councillors regard planning as an important policy-making activity. It is argued that in spite of the lack of success of local planning in terms of approved plans, it has been successful in encouraging local political debate and thereby contributed to the general decision-making process.

2-Diazo-1-(1,1-dioxothio-morpholin-4-yl)ethanone.

In the molecule of the title compound, C6H9N3O3S, at 105 K, the six-membered ring is predominantly found in the chair conformation, with 1.89 (14)% in the boat conformation. In the crystal structure, there are five intermolecular C—H⋯O=C and C—H⋯O=S contacts less than 2.6 Å, as well as a weak C—H⋯N=N interaction to the diazo group.