92,164 research outputs found
Novel hardware and software solutions for a complete linear and non-linear microwave device characterization
No full textF. Pisani. — Traité pratique d'analyse chimique qualitative et quantitative. — F. Alcan, éditeur
No full textRosenthal Léon. F. Pisani. — Traité pratique d'analyse chimique qualitative et quantitative. — F. Alcan, éditeur. In: Revue internationale de l'enseignement, tome 42, Juillet-Décembre 1901. p. 70
Per una valorizzazione turistica dei Monti Pisani
No full textPropone una serie di iniziative per valorizzare il territorio e l'ambiente dei Monti Pisani a fini turistici ed escursionistic
Tropos ligand for the asymmetric addition of phenylboronic acid to enones
No full textTROPOS LIGAND FOR THE ASYMMETRIC ADDITION OF PHENYLBORONIC ACID TO ENONES
P. Scafato, F. Caprioli, L. Pisani, C. Rosini
Dipartimento di Chimica, Università degli Studi della Basilicata, via N. Sauro, 85; Potenza.
e-mail: [email protected]
The asymmetric conjugate addition of arylboronic acids to activated olefins is nowadays an efficient method for the stereoselective construction of C(sp2)-C(sp3) bonds, given the large spectrum of substrates which can be used and the availability of many different chiral ligands.1 In this context, phosphoramidites certainly constitute a class of versatile and easily tunable ligands.2
We report herein the asymmetric addition of phenylboronic acid to different cycloalkenones with both the tropos phosphoramidite (S)-L1 and the non tropos (S)-L2 ligand. Different enantioselectivities have been obtained, mainly depending on the ring size of the substrates, with (S)-L1 affording higher e.e. values than (S)-L2. These results can been explained reasoning that, only for the tropos phosphoramidite, a “chiral pocket” is formed when the ligand links to the metal atom.
References:
1) (a) Fagnou, K.; Lautens, M. Chem. Rev. 2003, 103, 169-196; (b) Hayashi, T.; Yamasaki, K. Chem. Rev. 2003, 103, 2829-2844.
2) a) Boiteau, J.-M.; Imbos, R.; Minnaard, A. J.; Feringa, B. L. Org. Lett. 2003, 5, 681-684.
3) P. Scafato, G. Cunsolo, S. Labano, C. Rosini, Tetrahedron 2004, 60, 8801-8806
Accuracy of a multiport network analyzer
No full textThe accuracy of a multiport vector network analyzer, which uses a new calibration concept, has been compared with a 2-port network analyzer that implements the classical TRL procedure. The accuracy assessment is based on the analysis of the error propagation due to the connectors repeatability, both of the used standards and the measurands. The comparison, performed in the 2-18 GHz band on devices fitted with APC-7 mm connectors, proved the high accuracy reached by a multiport system which can qualify for metrological applications
Comparison between a vector multiport network analyzer and the national S-parameter measurement system
No full textA multiport vector network analyzer based on a new calibration concept, has been compared with the P-port S-parameter National measurement system at IENGF. The measurements were performed on precision 7 mm standard components and exhibited an optimum agreement. These results open the possibility to use the new multiport network analyzer for certification measurements of multiport device
I.3. Pietro Uberti, Ritratto del doge Alvise Pisani
No full textIl testo analizza le committenze scultoree che la famiglia Pisani di Santo Stefano indirizzò nella prima metà del Settecento a Francesco Bertos per la decorazione del palazzo di famiglia a Venezia e della villa di Stra.The text analyses the sculptural commissions that the Pisani family of Santo Stefano addressed in the first half of the 18th century to Francesco Bertos for the decoration of the family palace in Venice and the villa in Stra
Maternal and neonatal MTHFR-C677T mutation: a case report
No full textHomozygosis for the thermolabile variant (C677T) of the methylene-tetrahydropholate reductase (MTHFR) gene has been related to a high incidence of neural tube defects, pre-eclampsia, retardation in fetal growth and hyperhomocysteinemia. The latter represents a known risk factor for thrombosis. We report the case of a newborn with severe cerebral damage and neonatal epilepsy that needed treatment with antiepileptic drugs. The mother was to be found homozygote for the C677T variant of the MTHFR gene and the child was to be found heterozygote for the same mutation. We underline the possible correlation between the fetal-perinatal adverse events and the mother's genetic metabolic risks. © 2005 - IOS Press and the authors. All rights reserved
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