- Enantioselective synthesis of cyclic and linear diamines by imine cycloadditions
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Imine is one of the most versatile functional groups in chemistry and biochemistry fields. Although many biochemical reactions involve imine formation, the inherently unstable property of N-alkyl-α,β-unsaturated imines still hindered their utilization in organic synthesis. In this article, we described that the N-alkyl-α,β-unsaturated imines, which prepared from alkylamines and acrolein, could smoothly react through [4 + 4] cycloaddition to give eight-membered diazacyclooctane derivatives in excellent yields. Under a similar condition, in the presence of formaldehyde, the [4 + 2] and [4 + 2 + 2] cycloadditions could lead to the formation of six-membered hexahydropyrimidine or eight-membered triazacyclooctanes, depending on the substituent of aldehydes. Moreover, an easy functional group manipulation of the cyclic products obtained from these cycloadditions can provide variously substituted chiral linear diamines. We can utilize these novel reactivities to reveal the unknown and essential properties of many biological processes that involve N-alkyl-unsaturated imines.
- Chang, Tsung-Che,Pradipta, Ambara R.,Tanaka, Katsunori
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p. 1160 - 1168
(2020/07/08)
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- Proline-catalyzed asymmetric synthesis of syn - And anti -1,3-diamines
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A general organocatalytic strategy for asymmetric synthesis of both syn/anti-1,3-diamines has been developed. The strategy employs proline-catalyzed sequential α-amination and Horner-Wadsworth-Emmons (HWE) olefination of aldehydes as the key step where sy
- Kumar, Pradeep,Jha, Vishwajeet,Gonnade, Rajesh
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p. 11756 - 11764
(2014/01/06)
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- Preparation, Characterization, Cytotoxicity, and Mutagenicity of a Pair of Enantiomeric Platinum(II) Complexes with the Potential to Bind Enantioselectively to DNA
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The synthesis of a pair of enantiomeric Pt(II) complexes, and (eap = N,N-diethyl-2,4-pentanediamine), designed to bind enantioselectively to GpG and ApG sequences of DNA is described. The in vitro cytotoxicity of each of the enantiomers toward murine leukemia and human bladder tumor cells has been measured. The R,R enantiomer was found to be more active in the leukemia cells, but the difference was not as great as expected (IC50; R,R 14 μM, S,S 33 μM). In the bladder tumor cell line, no significant difference in activity was found. The two enantiomers had similar mutagenicity in the Salmonella reversion assay, but the R,R enantiomer was more cytotoxic in the bacterial cells. A structural analysis of the R,R enantiomer revealed that the ligand adopted an unexpected configuration, and a strain energy minimization analysis showed that this was a consequence of interactions between the diamine ligand and the dichloro ligands. The significance of the structural preferences with respect to the lower than expected enantiospecificity is discussed. Crystals of are monoclinic; space group, P212121; a = 7.909(5), b = 12.972(9), and c = 13.269(12) Angstroem; Z = 4; and the structure was refined to R = 0.025 (1657F).
- Vickery, Kymberley,Bonin, Antonio M.,Fenton, Ronald R.,O'Mara, Shaun,Russell, Pamela J.,et al.
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p. 3663 - 3668
(2007/10/02)
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- ASYMMETRIC NITROGEN-41 STEREOCHEMISTRY OF BICYCLIC 1,2-CIS-DIAZIRIDINES
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The twisting of 5- and 6-membered rings in bicyclic cis-diaziridines-1,5-diazabicyclo(3.1.0)hexanes 12-17 and 1,6-diazabicyclo(4.1.0)heptane 18-is a rapid process in the time scale of 1H- and 13C-NMR even at -80 deg C.According to the 1H- and 13C-NMR spectra, 1,5-diazabicyclo(3.1.0)hexanes 12, 13, 15a,b and 16a, b do, exist mostly in the boat form; only the introduction of endo substituents into position 3 or 6 leads to the population of the chair, as is the case with 14 and 17. 2,4-Dialkyl substituted 1,5-diaza- and 1,3,5-triazabicyclo(3.1.0)hexanes are formed via a transition cyclization state similar in its geometry to the initial chair-shaped N-chlorodi(tri)azanes.
- Shustov, G.V.,Denisenko, S.N.,Chervin, I.I.,Asfandiarov, N.L.,Kostyanovsky, R.G.
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p. 5719 - 5732
(2007/10/02)
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- Conformational Analysis of Coordination Compounds. XI Molecular Structure of Tetraammine-cobalt(III) Dithionate
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The crystal structure of tetraamminecobalt(III) dithionate dihydrate (NH3)4>(S2O6)1.5,2H2O has been determined by X-ray structure analysis.The crystals are triclinic with the space group P1, with a 11.43, b 11.65, c 7.78 Angstroem, α 100.48, β 105.95 deg, and γ 75.95 deg.The structure has been refined by least-squares methods with anisotropic temperature factors to an R value of 0.043 for 2654 reflections.The six-membered diamine chelate ring has a skew-boat conformation in which the two methyl groups are in equatorial orientations.A strain-energy-minimization calculation for the complex reveals an energy difference of 8. 3 kJ mol-1 between the preferred skew-boat conformation and the chair conformation.The calculated minimum-energy geometry for the skew-boat conformation is in good agreement with the observed structure for the chelate ring in the dithionate salt.The 1H n.m.r. spectra of this complex and other complexes of the chiral isomer of pentane-2,4-diamine are discussed in terms of the observed structures and the conformational analysis
- Hambley, Trevor W.,Hawkins, Clifford J.,Palmer, Judith A.,Snow, Michael R.
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