Characterisation of natural indigo and shellfish purple by mass spectrometric techniques

Two analytical methods based on mass spectrometry were used in the characterisation of constituents of natural indigo prepared from the leaves of Indigofera tinctoria, and of shellfish purple prepared from the hypobranchial glandular secretions of Murex trunculus, following old recipes. On-line pyrolysis gas chromatography in the presence of hexamethyldisilazane followed by mass spectrometric analysis (Py-silylation/GC/MS), and direct exposure mass spectrometry (DE-MS), were used. Extensive fragmentation of indigoid dyes was obtained by Py-silylation/GC/MS. The following molecular markers were highlighted, which are useful for identification purposes: 1,2-dihydro-3H-indol-3-one for indigoid dyes, 1,3-dihydro-2H-indol-2-one for indirubine, and 6-bromo-1,2-dihydro-3H-indol-3-one for shellfish purple. Using DE-MS, 6,6'dibromoindigotine, monobromoindigotine and indigotine were identified as the main components, and the presence of tyrindoxyl, one of the dye precursors, was also assessed.     

Anelli con unica decomponibilità in fattori primi ed un problema di intersezioni complete

La prima redazione manoscritta di questo lavoro, che avevo iniziato e quasi concluso personalmente, presentava una lacuna tutt'altro che facile da colmare nella dimostrazione del teorema di Noether. P. Salmon ha superato questa difficoltà mediante gli sviluppi contenuti al n. 9, E.E' inoltre dovuto a Salmon il teorema 1 del n. 9 con cui viene sostituita una proprietà più limitata da me ottenuta in altro modo. Coll'uso del risultato di Salmon si perviene compiutamente al primo teorema del n. 11.Aldo Andreotti.     

Amberlyst 15: A Practical,Mild and Selective Catalyst for Methyl Esterification of Carboxylic Acids.1

Mild and selective methyl esterification of carboxylic acids are realized using Amberlyst 15 as acid catalyst in methanol. No race mization, epimerization or ketalization products have been observed with this method. Excellent results are obtained in the esterifications of bile acids.     

Synthesis and antibacterial activity of trinems bearing nitrogen derivatives at C(4)

Optimization of the antibacterial activity of 4-amino trinem, obtained through chemical modification of the basicity of the amino group at position 4, has led to the identification of a very interesting compound characterized by a broad spectrum of activity includingPseudomonas aeruginosa.Medicines Research Centre, GlaxoWellcome S.p. A Via A. Fleming 4, 37100 Verona, Italy. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1553–1559, November, 1998.     

Regioselective synthesis of 1,3,5- and 1,3,4,5-substituted pyrazoles via acylation of N-Boc-N-substituted hydrazones

Acylation of N-Boc-N-methylhydrazones followed by TFA treatment affords regioselective access to substituted pyrazoles. Both regioisomers of 1-methyl-3,5-disubstituted-1H-pyrazoles can be selectively obtained. This procedure can also be employed for the regioselective preparation of fully substituted 1H-pyrazoles.     

Capillary pressure and contact line force on a soft solid

The surface free energy, or surface tension, of a liquid interface gives rise to a pressure jump when the interface is curved. Here we show that a similar capillary pressure arises at the interface of soft solids. We present experimental evidence that immersion of a thin elastomeric wire into a liquid induces a substantial elastic compression due to the solid capillary pressure at the bottom. We quantitatively determine the effective surface tension from the elastic displacement field and find a value comparable to the liquid-vapor surface tension. Most importantly, these results also reveal the way the liquid pulls on the solid close to the contact line: the capillary force is not oriented along the liquid-air interface, nor perpendicularly to the solid surface, as previously hypothesized, but towards the interior of the liquid.     

Preparation of bicyclo[3.2.0]heptane-2-endo,7-endo-diols: 1,3-diols with a chiral rigid backbone

The easily available bicyclo[3.2.0]hept-3-en-6-ones (1a-f) have been converted into the corresponding bicyclo[3.2.0]heptane-2-endo,7-endo-diols (4a-f) in an efficient and stereoselective fashion. This preparation opens a route to a family of 1,3-diols with a chiral rigid backbone, potentially suitable as nonracemic precursors for bidentate ligands in asymmetric synthesis.     

Approach to a better understanding and modeling of (S)-dihydrofuran-2-yl, (S)-tetrahydrofuran-2-yl-, and furan-2-yl-β-dialkylaminoethanol ligands for enantioselective alkylation

This paper outlines our efforts to study the influence of an oxygen atom adjacent to the stereogenic center of β-aminoalcohol derivatives used as ligands for catalysts in the asymmetric alkylation of aldehydes. Thirty-four enantiomerically pure (S)-dihydrofuran-2-yl, (S)-tetrahydrofuran-2-yl-, and furan-2-yl-β-dialkylamino alcohols have been prepared from 1,4:3,6-dianhydromannitol, 1,4:3,6-dianhydrosorbitol, and aminoacids, and then have been evaluated as ligands for the enantioselective addition of diethylzinc to benzaldehyde. Attention has been focused on the structural features governing the extent of chiral induction, the reaction rate, and the chemical yield of 1-phenyl-1-propanol which has been promoted by this wide collection of β-dialkylamino alcohols.