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TO WHAT EXTENT THE NMR “MOBILE PROTONS” ARE RELEVANT FOR RESTRICTED ROTATIONAL … H N N N N H (HOH 2 C) 2 H 3 CC-HN N N O 2 N 5 H 6 H O O H 4 2 H H H 363 K CH 3 Piperazine Piperazine H-2-e H-4a CH 2 OH CH 2 OH H-2a SER-NH D-NH OH Pip-NH H-6-e, -a H-5-e H-2-e H-4-a H-2-a CH 2 OH Piperazine CH 3 SER-NH D-NH H-5-e H-6-a, -e OH Pip-NH CONCLUSIONS A rapid and efficient access to highly elaborated enantiopure melamines based on serinols was described. To the title report question,our answer consists of considering (i) primarily, the NH protons, involved in partial double 49
OANA MOLDOVAN, PEDRO LAMEIRAS, ERIC HENON, FLAVIA POPA, AGATHE MARTINEZ, ET ALL bonds, as very relevant for distribution of rotamers, dynamic behavior and sterically conditioned relationships with the solvent; (ii) the OH protons, indicative for solvation effects as intra- -OH…HO- or intermolecular -OH…HN< associations determining the stability of ground states. EXPERIMENTAL SECTION General. Melting points are uncorrected; they were carried out on ELECTROTHERMAL ® instrument. Conventional NMR spectra were recorded on a Bruker ® AM300 instrument operating at 300 and 75 MHz for 1 H and 13 C nuclei respectively. VT NMR experiments were performed on a Bruker ® DMX500 instrument. All NMR spectra were measured in anhydrous commercially available deuteriated solvents. The 13 C NMR description of compounds exhibiting frozen rotamers at room temperature was made by considering them as one global structure. Multiple δ C values for the same-labelled position means mixture of rotamers. Some specific abbreviations were used: bd (broad doublet) and bm (broad multiplet), p-NPh (p-nitrophenyl).TLC was performed by using aluminium sheets with silica gel 60 F 254 (Merck ® ); flash column chromatography was conducted on Silica gel Si 60 (40–63 μm, Merck ® ). All visualisations were realised in UV at 254 nm. IR spectra were performed on a Perkin-Elmer ® Paragom FT-IR spectrometer. Only relevant absorptions are listed [throughout in cm -1 : weak (w), medium (m) or (s) strong]. Microanalyses were performed on a Carlo Erba ® CHNOS 1160 apparatus. Mass spectra (MS) were recorded on a Bruker ® Esquire Instrument. Specific rotations were measured on a POLAMAT ® Karl-Zeiss Jena instrument. Full characterisation and synthesis of compounds I and II we reported in detail elsewhere [2b]. Typical procedure for the synthesis of compounds I-2a-c and II-3a-c. Preparation of compound I-2c To anh. K 2 CO 3 (1.512 g, 100%, 10.944 mmol) suspended in anh. THF (100 ml), solid 2-amino-2-(hydroxymethyl)propane-1,3-diol (TRIS, 1.325 g, 10.944 mmol) was added with vigorous stirring. The resulted suspension was cooled at -15 °C when cyanuric chloride (2.018 g, 10.944 mmol) as clear anh. THF (25 ml) solution was injected rapidly. The reaction mixture was let gently to reach room temperature and was kept as such for additional 24 hrs. with stirring. After this period, TLC monitoring indicated the intermediate 2,4-dichloro-6-{[1,3-dihydroxy-2-(hydroxymethyl)prop-2-yl]amino}-s-triazine 1c as a single spot (eluent acetone : ligroin 2:1, R f = 0.80). Freshly prepared (4S,5S)-5-amino-4-(4-nitrophenyl)-1,3-dioxane (I, DX-NH 2 ) (2.452 g, 100%, 10.944 mmol) and anh. K 2 CO 3 (1.512 g, 100%, 10.944 mmol) were added and the reaction mixture was heated at reflux (65 °C) for 12 hrs. (TLC monitoring, eluent toluene : isopropanol 2:1, R f = 0.80). When I and 1c were detected in small traces only, the reaction mixture was cooled at room temperature. 50
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GHOLAM HOSSEIN FATH-TABAR, ALI REZA
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MODJTABA GHORBANI symmetric but it
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MODJTABA GHORBANI group can be comp
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MODJTABA GHORBANI 10. P.V. Khadikar
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HOSSEIN SHABANI, ALI REZA ASHRAFI,
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MIRCEA V. DIUDEA, CSABA L. NAGY, PE
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STUDIA UBB. CHEMIA, LV, 4, 2010 WIE
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WIENER INDEX OF MICELLE-LIKE CHIRAL
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WIENER INDEX OF MICELLE-LIKE CHIRAL
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STUDIA UBB. CHEMIA, LV, 4, 2010 TUT
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TUTTE POLYNOMIAL OF AN INFINITE CLA
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TUTTE POLYNOMIAL OF AN INFINITE CLA
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ALI REZA ASHRAFI, HOSSEIN SHABANI,
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MOHAMMAD A. IRANMANESH, A. ADAMZADE
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RALUCA O. POP, MIHAI MEDELEANU, MIR
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MELINDA E. FÜSTÖS, ERIKA TASNÁDI
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STUDIA UBB. CHEMIA, LV, 4, 2010 APP
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APPLICATION OF NUMERICAL METHODS IN
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APPLICATION OF NUMERICAL METHODS IN
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VLADIMIR R. ROSENFELD, DOUGLAS J. K
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MAHSA GHAZI, MODJTABA GHORBANI, KAT
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MAHSA GHAZI, MODJTABA GHORBANI, KAT
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M. GHORBANI, M. A. HOSSEINZADEH, M.
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MONICA STEFU, VIRGINIA BUCILA, M. V
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MONICA STEFU, VIRGINIA BUCILA, M. V
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MAHBOUBEH SAHELI, RALUCA O. POP, MO
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MAHBOUBEH SAHELI, RALUCA O. POP, MO
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FARZANEH GHOLAMI-NEZHAAD, MIRCEA V.
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MAHBOUBEH SAHELI, MIRCEA V. DIUDEA
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MAHBOUBEH SAHELI, ALI REZA ASHRAFI,
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STUDIA UBB. CHEMIA, LV, 4, 2010 OME
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OMEGA POLYNOMIAL IN CRYSTAL-LIKE NE
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OMEGA POLYNOMIAL IN CRYSTAL-LIKE NE
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STUDIA UBB. CHEMIA, LV, 4, 2010 CLU
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CLUJ CJ POLYNOMIAL AND INDICES IN A
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ALI REZA ASHRAFI, ASEFEH KARBASIOUN
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POPA IULIANA, DRAGOŞ ANA, VLĂTĂN
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CRISTINA BISCHIN, VICENTIU TACIUC,
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MIRCEA V. DIUDEA CONCLUSIONS The re
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