3-Azawurtzitan und 3(4 → 5)abeo-3-Azawurtzitan

3-Azawurtzitane and 3(4 → 5)abeo-3-Azawurtzitane 3-Azawurtzitane (14) and 3(4 → 5)abeo-3-azawurtzitane (15) as well as derivatives thereof are described. The known tricyclic unsaturated ketone 1 was transformed to the properly functionalized endo-amines 3, 5 and 12. Entry to the azawurtzitane system and its corresponding abeo-compounds was achieved by three different cyclization procedures: aminomercuration with mercuric acetate in water (3 → 14, 5 → 16) , olefin amination with mercuric acetate in dimethyl sulfoxide (3 → 18, 5 → 20 + 21) and intramolecular attack at an epoxide (12 → 24 + 25). Molecular rearrangements of 3-azawurtzitanes to 3(4 → 5)abeo-3-azawurtzitanes and vice versa are described involving neighbouring group participation of the N (3) atom.     

Anti- and syn-Tricyclo [4.2.1.12,5]decane. Preliminary communication

The two novel tricyclic C₁₀H₁₆ compounds anti- and syn-tricyclo [4.2.1.1^2,5]- decane ( 16 and 17 , respectively) were synthesized starting either from the photodimer 2 (anti) or the two cycloaddition products 8 (anti) and 9 (syn).     

Infrared spectroscopy of acetone-water liquid mixtures. II. Molecular model

In aqueous acetone solutions, the strong bathochromic shifts observed on the OH and CO stretch infrared (IR) bands are due to hydrogen bonds between these groups. These shifts were evaluated by factor analysis (FA) that separated the band components from which five water and five acetone principal factors were retrieved [J. Chem. Phys. 119, 5632 (2003)]. However, these factors were abstract making them difficult to interpret. To render them real an organization model of molecules is here developed whose abundances are compared to the experimental ones. The model considers that the molecules are randomly organized limited by the hydrogen bond network formed between the water hydrogen atoms and the acetone or water oxygen atoms, indifferently. Because the oxygen of water has two covalent hydrogen atoms which are hydrogen-bonded and may receive up to two hydrogen atoms from neighbor molecules hydrogen-bonded to it, three types of water molecules are found: OH2, OH3, and OH4 (covalent and hydrogen bonds). In the OH stretch region these molecules generate three absorption regimes composed of nu3, nu1, and their satellites. The strength of the H-bond given increases with the number of H-bonds accepted by the oxygen atom of the water H-bond donor, producing nine water situations. Since FA cannot separate those species that evolve concomitantly the nine water situations are regrouped into five factors, the abundance of which compared exactly to that retrieved by FA. From the factors' real spectra the OH stretch absorption are simulated to, respectively, give for the nu3 and nu1 components the mean values for OH2, 3608, 3508; OH3, 3473, 3282 and OH4, 3391, 3223 cm(-1). The mean separations from the gas-phase position which are respectively about 150, 330, and 400 cm(-1) are related to the vacancy of the oxygen electron doublets: two, one, and zero, respectively. No acetone hydrate that sequesters water molecules is formed. Similarly, acetone produces ten species, two of which evolve concomitantly. Spectral similarities further reduce these to five principal IR factors, the abundance of which compared adequately to the experimental results obtained from FA. The band assignment of the five-acetone spectra is given.     

SPECTROSCOPIC STUDIES ON A RETINYLIDENE-IMINE-TETRAFLUOROBORATE

Abstract— N -retinylidene-butyl-l-aminium tetrafluoroborate (NRBH+BF₄^-) was used to determine the frequencies of the free (non-hydrogen-bonded) v (N+-H) and v (C=NH+) vibrations and their anharmon-icity constants. For this purpose the Fourier-transform IR and near-IR (overtone) spectra were recorded. The visible-UV spectra were also taken. The results locate the free v (N+-H) band at about 3250 ± 50 cm^-1; the vibration has normal anharmonicity while v (C=NH+) is very nearly harmonic. The UV and IR spectra show that the Schiff base is protonated, but that the proton is only very weakly hydrogen-bonded to the anion. Therefore, in this respect, NRBH+BF₄^- is a good model for the hydrogen-bonding environment of the region around the nitrogen of rhodopsin chromophores.     

Heterotricyclodecane. XXVI. 2,6-Dioxatricyclo [3.3.2.03,7]decan,ein neuartiges isomers von 2,6-dioxaadamantan

2,6-Dioxatricyclo [3.3.2.0^3,7]decane, a Novel Isomer of 2,6-Dioxaadamantane Restriction among the great number of possible diheterotricyclodecanes to such with a carbocyclic 8membered ring (cyclooctane) as basic skeleton, which is crosswise bridged by two heteroatoms, and restriction to 5-, 6- and 7membered heterocyclic rings results in the isomeric diheterotricyclodecanes of the following five different structural types: 2,6-diheteroadamantane (a) , 2,7-diheteroisotwistane (b) , 2,7-diheterotwistance (c) , 2,8-diheterohomotwistbrendane (d) , and 2,6-diheterotricyclo [3.3.2.0^3,7]decane (e ; s. Scheme 1). Starting from a suitably C (5)^o(2)-functionalized 2,7-dioxaisotwistane, first representatives with the hitherto unknown skeleton of type e were prepared by molecular rearrangement involving neighboring group participation: 2,6-dioxatricyclo [3.3.2.0^3,7]decane (41) and the derivatives 34–40 thereof (Scheme 7).     

The adamantane rearrangement of syn- and anti-Tricyclo[4.2.1.1.12,5] decane. Part II. Rearrangements initiated by regioselective formation of carbocations at C(3) and C(9)

The endo- and exo-alcohols 5–12 of syn-( 1 ) and anti-tricyclo[4.2.1. 1^2.5]decane ( 2 ) were treated with BF₃/Et₃SiH (ionic hydrogenation) in order to study the behaviour of the corresponding regioselectively generated carbocations at C(3) ( a (syn), b (anti)) and C(9) ( c (syn), d (anti)). The anti-hydrocarbon 2 is practically the sole product obtained starting with the four 3-alcohols (via a → b from 5 and 6 (syn) and via b from 9 and 10 (anti)). The four 9-alcohols in each case yield a mixture of 2-endo, 3-endo- ( 3 ) and 2-exo,3-exo-trimethylene-8,9,10-trinorbornane (4) (via c → e from 7 and 8 (syn) and via d → f from 11 and 12 (anti)), but no hydrocarbon 2 , i.e. none of the 1,3-H shifts c → a and d → b is involved.     

Isolation of cytotoxic chondropsins, macrolide lactams from the New-Caledonian marine sponge Psammoclemma sp. and electrospray ion trap multiple stage MS study of these macrolides

Psammoclemma sp. (Phoriospongiidae) was selected for study through biological screening carried out in New Caledonia. The crude extract of Psammoclemma sp. was highly active on KB cells and its fractionation led to the isolation of two macrolides chondropsin A 1 and 73-deoxychondropsin A 2. The complex structures were elucidated by a combination of spectroscopic methods (NMR, ESI-MS/MS). These known compounds were evaluated for their cytotoxic activity towards several tumor cell lines and exhibited an IC50 of approximately 10(-10) M. Flow-cytometric analysis revealed that chondropsin A 1 and 73-deoxychondropsin A 2 blocked the entry of HL 60 and KB cells into G2/M phase, leading to cell death by apoptosis.     

Tricyclo [3.3.2.03,7]decan (9-Homo-nor-adamantan) Synthese und Umwandlungen

Tricyclo[3.3.2.0^3,7]decane (9-Homo-nor-adamantane). Synthesis and Transformations A synthesis of tricyclo [3.3.2.0^3,7]decane (=9-homo-nor-adamantane; 1 ), which belongs to the adamantaneland, a family of nineteen isomeric C₁₀H₁₆ hydrocarbons, is described, as well as derivatives thereof. Treatment of protoadamantan-5endo-ol (11) with either thionyl chloride or phosphorus pentachloride yielded under rearrangement the chloride 18 , and solvolysis of the 5endo-chloro-protoadamantane (16) led to the acetate 26, 18 and 26 having both the tricyclo [3.3.2.0^3,7]decane skeleton. Subsequent transformations gave the title compound 1 as well as the corresponding olefin 8 .     

The Novel Adamantane Isomer 2,5-Trimethylenenorbornane (Tricycio-[5.3.0.3,9]decane, 4-Homotwistbrendane)

A synthesis of the novel C₁₀H₁₆ hydrocarbon 2,5-trimethylenenorbornane (tricyclo[5.3.0.0^3,9]decane, 1 ), one of the 19 members of the ‘adamantaneland’, and its Lewis-acid-catalyzed rearrangement is described.