Substituenteneffekte in den13C-NMR-Spektren von diastereomeren Chalkondihalogeniden, 10. Mitt.: Erste Synthese und Konfigurationsbestimmung vonthreo-Chalkonbromhydrinen

Summary The first synthesis ofthreo chalcone bromohydrins was realized by reaction oftrans chalcone epoxides with SnBr₄ in molar ratios from 1:1 to 2:1. The compounds were obtained in high yields and isomeric purity. Their configuration was determined asthreo by different methods based on¹³C-NMR shifts of C- and C- atoms.

     

Chemical Interactions by Low-Energy Electron-Induced X-Ray Emission Spectroscopy, LEXES

 The possibilities presented by low-energy electron-induced X-ray emission spectroscopy to study chemical interactions in solids are discussed. Examples of change observed for the emissions between core levels as a function of the chemical environment of the emitting atoms are given. By comparing the partial densities of the valence states associated to each type of atoms in the compound, it is shown that the strength of the metal-ligand interactions can be obtained. Information on the charge densities around each type of atoms can be deduced. Application to the study of the interactions at the atomic scale to solid–solid interfaces is presented.     

Preparation of ethyl 5(s),6-epoxy-3(r)-(methoxymethoxy)hexanoate: a key chiral intermediate for mevinolin and compactin.

The synthesis of Ethyl 5(S),6-Epoxy-3(R)-(methoxymethoxy)hexanoate, a key chiral synthon for the β-hydroxy-δ-lactone portion of Mevinolin and Compactin, $\text{via}$ a regiospecific ring opening of a tetrahydrofuran derivative by dimethylboron bromide, is described.     

Thermophilic fermentation of hydrolysates

Lignocellulosic biomass has great potential as a cheap feedstock in biological processes to produce biofuels or chemicals; however, dilute acid pretreatment at high temperatures produces undesirable compounds. Toxicity tests were done with inhibitors in standard media, to predict the growth-limiting effects on thermophilic strains. The 22 inhibitors included furfural, levulinic acid, acetic acid, and cinnamaldehyde. Neutralizing reagents and additional treatment steps have been tested.     

The nuts and bolts of distance determination and zero- and double-quantum coherence in photoinduced radical pairs

We describe in some detail the new method of distance determination for a photoinduced radical pair. Emphasis is on giving the nuts and bolts of the calculations that result in analytical expressions for in- and out-of-phase electron spin echo (ESE) envelope modulations, pulse flip-angle dependencies, zero- and double-quantum coherences, and the distance between the two radicals. The theoretical results are illustrated by a set of recent experiments on photosynthetic reaction centers.     

δ-Santalolanaloga II Synthesen in der Isocamphanreihe, 28. Mitt.

The synthesis of 3-(3,3-dimethyl-2-exo-norbornyl)-2-methylprop-2-en-1-ol (3) and of 8-hydroxymethyl-8-methylcamphene (4) is described.3 and4 are analogues of -Santalol (1) with the allylic hydroxyl group in a position of two or three carbon atoms closer to the bicyclic nucleus compared to1. 4 is also an analogue to Patchenol® which is used sometimes to blend the patchouli oil. The odour impression of these compounds, of the pureendo-epimer of3, and of theendo-exo-mixture of3 are described and compared with the odour of1 and a further analogue whose synthesis has already been reported in a preceding paper [1].

Auszugsweise vorgetragen auf der gemeinsamen wissenschaftlichen Tagung der ÖPhG und DPhG am 11. September 1986 in Innsbruck. Die Synthese von4 wurde bereits am 15. März 1983 anläßlich des 9th International Congress of Essential Oils in Singapore vorgestellt.     

Etude des voies d'accès aux aminométhyl benzo[g]isoquinoléinediones-5,10. Mise en évidence d'une substitution anormale au cours de la réaction de Bischler-Napieralski en série diméthoxy-1,4 naphthalène

Under the conditions of the Bischler-Napieralski reaction the cyclization of 2-(1,4-dimethoxy and 1,4,8-trimethoxynaphthyl)ethylacetamides derivatives take place essentially at the 1 position by substitution of the 1-methoxy group. Nevertheless, 1-aminomethyl-9,10-azaanthraquinones are accessibles by condensation of 1-aminomethylisoquinoline-5,8-diones with a 1,4-diacetoxy-1,3-butadiene.     

Total synthesis of (-)-spirotryprostatin B: synthesis and related studies

The total synthesis of spirotryprostatin B, a cytostatic spiro[pyrrolidine-3,3'-oxindole] alkaloid, is described. The key step of the synthetic approach consists of the application of the MgI2-mediated ring-expansion reaction of a spiro[cyclopropane-1,3'-oxindole] with an aldimine, leading to rapid assembly of the spirotryprostatin core. The route documents the installation of the prenyl side chain by Julia-Kocieński olefination of a key aldehyde precursor, a transformation that ultimately allows for facile synthesis of analogues and facilitates structure-activity relationships studies.     

High yielding microwave-assisted synthesis of 2-(arylmethyl)amino-4-arylamino-6-alkyl-1,3,5-triazines

An efficient and practical procedure was developed to prepare novel 2-(arylmethyl)amino-4-arylamino-6-alkyl-1,3,5-triazines, starting from dicyandiamide and the corresponding arylamines under microwave irradiation and its scope is demonstrated with a number of examples. The valuable feature of this procedure included the short reaction times, high yields, and easy operation.