P,N-Containing cyclophanes with large helical hydrophobic cavities: prospective precursors for the design of a molecular reactor.

The highly effective self-assembly process between 2,4,6-tris(isopropyl)phenylphosphine or mesitylphosphine, formaldehyde and 1,4-bis(alpha-(4'-aminophenyl)isopropyl)benzene results in the formation of a novel type of heterocyclophane which is able to encapsulate organic molecules as well as being a potential ligand for transition metals inside the intramolecular cavity. Compounds of this type can be regarded as potential precursors for a new kind of molecular reactors.

Structures of copper(II) and manganese(II) di(hydrogen malonate) dihydrate; effects of intensity profile truncation and background modelling on structure models.

The crystal structures of the title compounds were determined with net intensities I derived via the background-peak-background procedure. Least-squares optimizations reveal differences between the low-order (0 < s < 0.7 A(-1)) and high-order (0.7 < s < 1.0 A(-1)) structure models. The scale factors indicate discrepancies of up to 10% between the low-order and high-order reflection intensities. This observation is compound independent. It reflects the scan-angle-induced truncation error, because the applied scan angle (0.8 + 2.0 tan theta) degrees underestimates the wavelength dispersion in the monochromated X-ray beam. The observed crystal structures show pseudo-I-centred sublattices for three of its non-H atoms in the asymmetric unit. Our selection of observed intensities (I > 3 sigma) stresses that pseudo-symmetry. Model refinements on individual data sets with (h + k + l) = 2n and (h + k + l) = 2n + 1 illustrate the lack of model robustness caused by that pseudo-symmetry. To obtain a better balanced data set and thus a more robust structure we decided to exploit background modelling. We described the background intensities B(H-->) with an 11th degree polynomial in straight theta. This function predicts the local background b at each position H--> and defines the counting statistical distribution P(B), in which b serves as average and variance. The observation R defines P(R). This leads to P(I) = P(R)/P(B) and thus I = R - b and sigma(2)(I) = I so that the error sigma(I) is background independent. Within this framework we reanalysed the structure of the copper(II) derivative. Background modelling resulted in a structure model with an improved internal consistency. At the same time the unweighted R value based on all observations decreased from 10.6 to 8.4%. A redetermination of the structure at 120 K concluded the analysis.

Highly selective formation of [4+2] and [4+3] cycloadducts of tetrahydroindenes generated in situ from a (1-alkynyl)carbene tungsten complex by the metalla-1,3,5-hexatriene route.

1-Amino-3-ethoxytetrahydro-3aH-indenes 8 can be readily generated together with pentacarbonyl(pyridine)tungsten in a template induced three-component reaction of [(1-cyclohexenyl)ethynyl]carbene tungsten complex 1 with secondary amines 2a-d and pyridine. Even though the compounds 8 are thermally quite unstable and undergo a fast rearrangement to tetrahydro-7aH-indenes 7. they can be trapped by formation of (rather strained) [4+2] cycloadducts 12 with maleimide 11. If 1-amino-3-ethoxytetrahydro-3aH-indenes 8 are generated in the presence of electron-poor alkynes 2a and 2b, they undergo a 1,5-shift to give tetrahydro-7aH-indenes 7, which in turn afford [4+2] cycloadducts 4a-d. Condensation of 1-tungsta-1,3,5-hexatrienes (3E)-5a-d with 1-metalla-1,3-butadienes 14 (M = Cr, W) give [4+3] cycloadducts 15a-e of tetrahydro-7aH-indenes 7 in good yields with high regio- and stereoselectivity.