1,721,348 research outputs found
The intramolecular interaction of thiophene and furan with aromatic and fluoroaromatic systems in some (3,3)meta(heterocyclo)paracyclophanes.
No full textPer studiare l' interazione di non legame tra sistemi eterociclici ed anelli aromatici, abbiamo sintetizzato una serie di [3,3]meta(eterociclo)paraciclofani contenenti piridina, tiofene, e furano collegati da due ponti CH2SCH2 alle posizioni para di un anello benzenico normale o tetrafluorosostituito.
Tali derivati sono conformazionalmente abbastanza flessibili da consentire all' anello eterociclico di adottare diverse disposizioni rispetto alla piattaforma benzenica (parallela sovrapposta, parallela sfalsata, bordo-faccia, ecc.), ma sufficientemente rigidi da opporre barriere energetiche determinabili sperimentalmente all' interconversione di queste conformazioni.
Lo studio del comportamento dinamico e statico tramite spettroscopia NMR a temperatura variabile, diffrattometria a raggi X, e metodi computazionali di questi sistemi modello ha consentito di evidenziare come l' interazione tra l' anello eterociclo e quello aromatico dipenda fortemente da fattori geometrici e sia solo in parte razionalizzabile sulla base di un' interpretazione dell' interazione aromatico/eteroaromatico basata solo su fattori polari (polar/π effect)
Non-bonding interactions involving fluoroaromatic compounds: from pi-stacking to complexation by cyclodextrins
No full textStereoselective organic catalysis or how to forget about metals and live happily thereafter
No full textThe interaction of pyridine, thiophene, and furan with aromatic and fluoroaromatic systems in (3.3)meta(heterocyclo)paracyclophanes
No full textHow organic molecules act on each other: from arene/heteroarene ionteractions to close halogen/halogen contacts in the solid state
No full text
Immobilization of organic catalysts : when, why, and how
No full textThis review article is divided in two parts. In the first part (Sections 2 and 3) selected examples of the publications that appeared in the literature in the period 2003-2005 in the field of immobilized organic catalysis are presented. When appropriate, the results of these publications are compared to those reported earlier and already discussed in a previous review article (see ref.[4]). On the basis of this survey, in Section 4 some general considerations about when and why a supported version of an organic catalyst is worth developing are proposed. In Section 4 a list of suggestions about how the process of immobilization should be carried out is also included, taking into account several factors such as the properties of the catalyst, the nature of the support, and the mode of connection of the catalyst to the support
Beta asymmetric induction in the reduction of N-alkylidenesulphinamides. Synthesis of optically active amines
No full textAsymmetric synthesis occurs in the reduction by LiAlH4 of optically active N-alkylidenesulphinamides; the sulphinamides thus obtained can be oxidized to optically active sulphonamides or cleaved to optically active amines of high optical purity
L'interazione non covalente tra sistemi aromatici ed eteroaromatici nei metaparaciclofani
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