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1.
The reaction of thiazolidines 2 and 7 with borane was investigated. It gave N-methylcysteamines 3 and 8 through thiazolidine ring opening. Sodium borohydride and lithium aluminum hydride were ineffective. 相似文献
2.
Celestino Angeli Renzo Cimiraglia Maurizio Persico Alessandro Toniolo 《Theoretical chemistry accounts》1997,98(1):57-63
We discuss the “three class” approximation to full multireference perturbation CI, which greatly reduces the computational
effort by restricting the summation of diagrams to determinants belonging to a subspace of the zero-order space. In the framework
of the CIPSI algorithm, we propose a new extrapolation procedure allowing recovery of the full “two class” results. The new
procedure is applied to complete active spaces (CAS) and to individually selected zero-order spaces. Comparison with a full
two class calculation on a CAS shows a reduction of computer time of one or two orders of magnitude in the tests presented
here, with an accuracy in the order of 0.1 kcal/mol. Our procedure can thus compete with the CASPT2 algorithm, specifically
conceived to deal with CAS. In the case of selected zero-order spaces, the speed-up is less dramatic but the method still
retains its advantages.
Received: 12 June 1997 / Accepted: 31 July 1997 相似文献
3.
Günther Snatzke Cristina Angeli Enio Decorte Flavio Moimas Biserka Koji-Prodi Ziva Ruzi-Toro Vitomir Sunji 《Helvetica chimica acta》1986,69(3):734-748
Hydrogenation of the ketone group in di-O-benzylderivative ( 8 ) of the known macrocyclic lactone zeralenone ( 7 ) using a novel chiral borane complex 3 . BH3, prepared in situ, proceeded at lower temperatures with moderate diastereoselectivity (~40%, d. e. at ?60°). Unsaturated diastereomers 9 and 10 were separated, and 9 converted into zeranol ( 11 ), a known anabolic agent. Restricted conformational mobility at lower temperatures is assumed for the intermediate 8 on the basis of the temperature-dependent CD spectra of its acetyl congeners 18 and 19 . X-Ray structure analysis of 7-O-acetylderivative ( 13 ) of 11 revealed the (R)-configuration at C(7). Two crystallographically independent H2O molecules are involved in the H-bonds, one of them (O(21)) rises the helices of the molecules of 13 along b. Small positive torsional angle [C(16)-]C(161)-C(1) [=O] (+19.3°), transoid(E) conformation of the lactone group, and nearly achiral arrangement of the C(11)-C(12) bond (torsional angle [C(11)-]C(12)-C(121)[C(161)] is ?93°) are the main conformational features that differentiate the macrocylic RAL (resorcinic-acid lactone) derivatives from the 6-membered lactone derivative 20 , studied earlier by CD. Consequently, the rules developed for the CD effects within conjugation band (around 270 nm), and n→π* band (around 255 nm) of the latter compound, cannot be applied the macrocyclic lactones. 相似文献
4.
Simone Carradori Marialuigia Fantacuzzi Alessandra Ammazzalorso Andrea Angeli Barbara De Filippis Salvatore Galati Anl Petzer Jacobus P. Petzer Giulio Poli Tiziano Tuccinardi Mariangela Agamennone Claudiu T. Supuran 《Molecules (Basel, Switzerland)》2022,27(22)
Neurodegenerative diseases (NDs) are described as multifactorial and progressive syndromes with compromised cognitive and behavioral functions. The multi-target-directed ligand (MTDL) strategy is a promising paradigm in drug discovery, potentially leading to new opportunities to manage such complex diseases. Here, we studied the dual ability of a set of resveratrol (RSV) analogs to inhibit two important targets involved in neurodegeneration. The stilbenols 1–9 were tested as inhibitors of the human monoamine oxidases (MAOs) and carbonic anhydrases (CAs). The studied compounds displayed moderate to excellent in vitro enzyme inhibitory activity against both enzymes at micromolar/nanomolar concentrations. Among them, the best compound 4 displayed potent and selective inhibition against the MAO-B isoform (IC50 MAO-A 0.43 µM vs. IC50 MAO-B 0.01 µM) with respect to the parent compound resveratrol (IC50 MAO-A 13.5 µM vs. IC50 MAO-B > 100 µM). It also demonstrated a selective inhibition activity against hCA VII (KI 0.7 µM vs. KI 4.3 µM for RSV). To evaluate the plausible binding mode of 1–9 within the two enzymes, molecular docking and dynamics studies were performed, revealing specific and significant interactions in the active sites of both targets. The new compounds are of pharmacological interest in view of their considerably reduced toxicity previously observed, their physicochemical and pharmacokinetic profiles, and their dual inhibitory ability. Compound 4 is noteworthy as a promising lead in the development of MAO and CA inhibitors with therapeutic potential in neuroprotection. 相似文献
5.
Arzu Gumus Murat Bozdag Atilla Akdemir Andrea Angeli Silvia Selleri Fabrizio Carta Claudiu T. Supuran 《Molecules (Basel, Switzerland)》2022,27(14)
A novel series of thiosemicarbazide-substituted coumarins was synthesized and the inhibitory effects against four physiologically relevant carbonic anhydrase isoforms I, II, IX and XII showed selective activities on the tumor-associated IX and XII isozymes. Molecular modeling studies on selected compounds 14a and 22a were performed. The binding modes of such compounds were determined assuming their enzymatically active structures (i.e., cinnamic acid) in the thermodynamically favored, and not previously explored, E geometry. Molecular modelling suggests multiple interactions within the enzymatic cavity and may explain the high potency and selectivity reported for the hCAs IX and XII. 相似文献
6.
M. Oklobdija G. Comisso E. Decorte T. Kova
C. Angeli F. Moimas P. Zanon F. Zonno R. Toso V. unji 《Journal of heterocyclic chemistry》1983,20(5):1335-1338
Attempting some new approaches to 5,11-dihyro-6H-pyrido[2,3-b][1,4]benzodiazepin-6-one ( 6 ), compounds 8, 10 and 11 were prepared. Ring enlargement of 4 into 6 failed, as well as condensation of 10 and 11 into ID, which is the potential precursor of pirenzepin (11-[2′-(4″-methylpiperazin-1″-yl)]acetyl derivative of 6 ) via an envisaged intramolecular Diels-Alder reaction. Model compounds 5 and 13 were prepared and their behaviour in analogous reactions explained the failures of the intended transformations of 4 , as well as of condensation of 10 and 11 . 相似文献
7.
The dissociation of SF5Cl and CF3I sensitized by multiphoton excitation of SF6 by a pulsed CO2 laser has been studied versus pressure, laser fluence, inert gas and optical frequency. Isotopic effects have been observed between 32SF5Cl/33SF5Cl and between 13CF3I/12CF3I and selectivity factors as high as α?1 = 1.57 or α = 1.23 obtained. 相似文献
8.
9.
The integration of constriction structures such as nanopores and nanochannels into fluidic devices discloses powerful biosensing capabilities that can be tuned to a wide range of analytes through conceptually simple size calibrations. The practical implementation of this tuning requires a nontrivial manipulation of matter at nanoscale with further requirements for low complexity and low-cost procedures that may be adapted to industrial production. Here, we review the recent progress on the fabrication techniques of nanopores and nanochannels, together with the efforts to realize their full biosensing potential by understanding and amending the problems still afflicting the measurement performed during operation. 相似文献
10.
Investigation at fourteen energies from 0.5 to 42 MeV and A 27 shows that a simple expression describes the σT(A,E) surface in the energy and mass number region mentioned above. For E 10 MeV the expression can be interpreted by the nuclear Ramsauer effect, while for E < 10 MeV a better approximation for the black-nucleus formula seems to be useful. The constant amplitude of oscillations suggests a weak volume absorption and a strong surface absorption. 相似文献