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Notes: Partial Synthesis and Oncostatic Properties of Pseudotubulosines, Analogues of Emetine and TubulosinePseudotubulosines, structural analogues of emetine and tubulosine, have been synthesized by either Pictet-Spengler or Bischler-Napieralski condensation from dihydrocorynantheal or corynantheidal. Spectral data, cytotoxic and oncostatic properties of these new alkaloids are described.

Notes: Monoterpene Alkaloids of Scaevola racemigera DÄNIKERNine alkaloids have been isolated from the aerial parts of Scaevola racemigera. Two of them are the known compounds cantleyine (1) and tetrahydrocantleyine (2). The seven others are novel alkaloids, strychnovoline (3), 6-O-nicotinoylstrychnovoline (4), 6-O-nicotinoyltetrahydrocantleyine (5), 6-O-(5-vinylnicotinoyl)tetrahydrocantleyine (6), racemigerine (7), 6,7-epoxyracemigerine (8), and scaevoline (9). The structures of the new compounds have been elucidated by their spectral data and confirmed by chemical correlations. Moreover, the absolute configuration of 2, which had not been previously determined, has been elucidated.

Notes: A variety of 2-deoxy-1-O-diphenoxylphosphoryl-hexopyranoses were generated in situ by a radical 2→1 migration of the phosphate group. The structures of the reactive rearrangement products were fully elucidated by NMR spectroscopy. Rate constants for this new rearrangement were determined fro a variety of substrates.

Notes: Quantum-chemical calculations employing a density-functional theory/Hartree-Fock hybrid method (B3LYP) have been used to explore the mechanistic details of the C—C and C—H bond-activation processes in propane mediated by a bare Fe+ ion. While the theoretically predicted results are in complete accord with all available experimental data, they give rise to a different mechanistic picture than envisaged previously. In contrast to earlier speculation, the activation barriers for the initial insertion steps of Fe+ into a C—H or C—C bond are found to be significantly below the Fe+ + C3H8 channel. The rate-determining steps for both, the C—C and the C—H bond activation branches of the [FeC3H8]+ potential-energy surface rather occur late on the respective reaction coordinates and are connected with saddle points of concerted rearrangement processes. The C—C bond activation, which leads to the exothermic reductive elimination of methane, occurs via the C—C inserted species and not as a side channel originating from a C—H inserted ion, as assumed hitherto. For the C—H bond-activation processes, which finally results in the exothermic expulsion of molecular hydrogen, two energetically similar reaction channels for an [1,2]-elimination exist. The results clearly show, that an [1,3]-H2-elimination mechanism cannot compete with the [1,2]-elimination paths, in line with the experimental findings. Overall, a lower energy demand for the reductive elimination of methane compared to the loss of H2 is obtained, straightforwardly explaining the preference of the former process observed experimentally.

Notes: Thirty-two sterols are identified in the sponge Hyrtios sp. In addition to fourteen monohydroxylated compounds, the sterol fraction contains eight functionalized sidechain sterols, three of them new: 3 β-hydroxy-24-norchol-5-en-23-al (19), (22-trans)-3 β-hydroxycholest-5, 22-dien-24-one (20) and (22R, 23R, 24S) or (22S, 23S, 24S)- 22,23-epoxy-24-methylchoest-5-en-3 β-ol (24). The probable biological origin, rather than artifact production, of these undescribed components is discussed.

Notes: Circular Dischroism of Heteroyohimbane-Type AlkaloidsCircular dichroism cannot be used directly to determine the C (3)-configuration of heteroyohimbines. A preliminary chemical transformation is necessary.

Notes: Isolation and Structure Elucidation of Pteridines (Lumazines) from Russula sp. (Basidiomycetes)Extensive chromatogaphic separations and spectroscopic investigations have led to the isolation and identification of several water-soluble pteridines from Russula sp., the so-called russupteridines, namely: 1-(5-amino-2-6-dioxo-1,2,3,6-tetrahydeopyrimidin-4-yl)amino-1-deoxy-D-ribitol (1; a pro-lumazine; first identification in a basidiomycete(; l-deoxy-l-(6-methyl-2-4,7-trioxo-1,2,3,4,7,8-hexahydro-pteridin-8-yl)-D-ribitol (3) and l-deoxy-1-(2,4,7-trioxo-1,2,3,4,7,8-hexahydeopteridin-8-yl)-D-ribitol (4); both compounds found for the first time in higher fungi; they belong to the components with the strongest violet-blue fluorescence in Russula sp.; riboflavine (6; now recognized as an important yellow colorant in a great many of Russula sp.); russupteridine-yellow I (= l-(6-amino-7-(N-fromylimino)-2,4-dioxo-1,2,3,4,7,8-hexahydropteridin-8-yl)-1-deoxy-D-ribitol; 5; a component with very strong fluorescence; the first derivative of the novel 6,7-diamino-lamazine); russupteridine-yellow IV (= l-deoxy-1-)(2,6,8-trioxo-2,4,5,6,7,8-hexahydro-1H-imidazolo[4,5-g]pteridin-4-yl)-D-ribitol (7)). Two further yellow russupteridines (yellow II and Yellow V) with very strong fluorescence have been isolated and characterized.

Notes: New Flavonoid Glycosides from Paeonia tenuifolia L.Two novel flavonoid glycosides have been isolated from the stamens of Paeonia tenuifolia, sexangularetin-3-O-yl β-D-sophoroside (1) and limocitrin-3-O-yl β-D-sophoroside (3). Their structures have been elucidated by spectroscopic means, mainly desorption chemical ionisation mass spectrometry and ID and 2D high-resolution 1H-NMR spectroscopy of their acety1 derivatives.

Notes: Macrocyclic Imides: Versatile Synthons in Ring-Enlargement ReactionsMacrocyclic imides differ from phthal- or succinimids in their increased electrophilicity. This property makes them versatile synthons for reactions with several nucleophiles. If a nucleophile is attached to the N-substituent of the imide, an intramolecular reaction will occur leading to ring-enlarged products. Use of N, O, and C nucleophiles for this synthetic pathway is reported. Synthetic transformations of e.g. cyclododecanone leads to 17-, 18-, or 19-membered macrolides, 11, 12, 15, 16, 21, 27, 30, in three to five steps.

Notes: Photochemical Cyclization of o-, m-, p-Allylanisoles and o-AllylanilinesThe compounds irradiated are summarized in Scheme 1. 2-Allylaniline and N-Alkyl Derivatives. Irradiation (ca. 3 h) of compounds 1-3 with a high pressure mercury lamp in benzene solution under argon (quartz vessel) gave in 40-80% yield the corresponding 2-methylindolines 20, 22 and 25, respectively (Scheme 3). Tetrahydroquinolines (23, 26) were formed only in minor amounts (0,5%). Irradiation in methanol solution yielded in addition to the indolines the 2-(2′-methoxypropyl)-anilines 21,24 and 27, respectively, in a ratio of ca. 0.3, 1.5 and 1.0 with respect to the indolines (Scheme 3). Similar results were obtained in ethanol solution. The observation that the photoreactions in benzene or methanol are not quenched by (E)-piperylene or sensitized by acetone suggests that the transformation starts from the singlet manifold of the aniline chromophor. As outlined in Scheme 11 it is proposed that the excited molecules undergo an intramolecular electron transfer to give an acceptor(olefinic side chain)/donor(aniline part) complex (EDA complex; see [28]) of type {a,b} in which the positive charge is mainly located at the nitrogen atom and the negative charge at C(3′) of the allyl substituent. That the negative charge resides predominantly at C (3′) - independently of alkyl substitution at C (3′) (see experiments cited in [26]) - may be due to electrostatic attraction of the charges. Thus, the following H-transfer occurs almost regiospecifically to give the singlet diradical c which cyclizes directly or via the spirocyclopropane derivative d to the indoline derivative 22. Intermediate d is also responsible for the formation of the 2′-methoxypropyl compounds: It is suggested that in the polar solvent methanol d is partially converted to the zwitterion e, the immediate precursor of 24. Experiments with the deuteriated reactants N-d-2 and 2′-d1-2 (Scheme 3) are in agreement with the proposed mechanism.N, N-Dialkyl-2-allylanilines and Allylanisoles. Upon irradiation in methanol or benzene, these aniline derivatives undergo cyclization to give as the only products the corresponding 2-cyclopropylanilines in 50-70% yield (Scheme 4). 2-, 3- and 4- allylated anisoles behave in the same way on irradiation (Schemes 6-8) as long as the allyl group carries no substituent (CH3, Cl) at the double bond (Schemes 9, 10). No photolytic cyclopropane ring formation is observed with the naphthalene derivatives 7, 8, 17 or 18 (Scheme 1). Experiments with the deuteriated compounds 2′-d1-4 and 1′, 1′-d2-11 - synthesized according to Scheme 2 - indicate that in all cases the cyclopropane formation occurs with concomitant 1,2 aryl migration (Schemes 5, 6) which characterizes the reaction as an aromatic di-π-methane rearrangement (Scheme 14). In contrast to the photoreactions described above the cyclopropane ring formation can be sensitized by acetone or quenched totally by (E)-piperylene. A comparison of the triplet energies (ET) of the aromatic and olefinic chromophor of the reactants (cf. Table 4) shows that the di-π-methane rearrangement is only effective when ET of the aryl part is lower than that of the olefinic part, but not by more than 20 kcal/mol. In substrates carrying substituents at the olefinic double bond the energy of T1 of the allyl group drops beneath that of the aryl part. In these cases no di-π-methane rearrangement is observed because an effective deactivation of T1 of the aryl part occurs by (E)/(Z) isomerization of the side chain as is demonstrated by the photochemical behaviour of compound 10 (Scheme 10). This concept seems to be of general significance for related di-π-methane rearrangements in cyclic systems (cf. Scheme 16; further examples: Scheme 15).